Questions tagged [sequence]

Questions on specifying order in and splicing of lists, including use of Mathematica Sequence objects.

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Limit of Taylor coefficients

I want to calculate the following limit: b[n_] := (D[1/(1 - t), {t, n}] /. {t -> 0})/Factorial[n] Limit[b[n], n -> ∞] (* Indeterminate *) where ...
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0 votes
1 answer
79 views

When running code to compute a sequence, loop variable gets set to a constant

I would like to write Mathematica code to read in a list of sequences, and print the sequence definition ($a_n$), along with the sequence evaluated at a few values of $n$. ...
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4 votes
0 answers
52 views

How to use Shortest[___] with Sequence pattern matching?

Shortest[] doesn't appear to work with Sequence s. Is this a bug or a feature? What can I do to force the following ...
0 votes
1 answer
22 views

Confusing result when pattern matching a BlankSequence (__) to a list, then calling unary function on the list [duplicate]

The following makes sense to me: In[1] = f[a, b] /. f[x__] -> x Out[1] = Sequence[a, b] In[2] = f[a, b] /. f[x__] -> {x} Out[2] = {a, b} However, the ...
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0 votes
0 answers
16 views

Difference Equation with Upper Boundary Condition, Lower Terms Not correct

I am struggling to understand the solution Mathematica is providing for the following recurrence relation As I have written a[i] I expected the following behavior <...
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10 votes
7 answers
637 views

Select data from a structured list

Let's suppose we have the following structure of data ...
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1 vote
2 answers
97 views

we want to get all possible values with $a_1$

I would appreciate it if somebody could help me with the following problem: Given $$a_{n+1}=\begin{cases} \dfrac{a_n}{2}& (a_n \: \text{even})\\ n{a_n}& (a_n \: \text{odd})\end{cases},\:a_8= ...
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0 votes
1 answer
62 views

Problem with For Loop when evaluating a recursive function at multiple points

I am running into problems with my For loop when trying to evaluate my expression. Fix some parameter values : ...
1 vote
3 answers
86 views

Rewrite the list without certain elements in the sequence

I have a list1: ...
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4 votes
4 answers
196 views

One-to-multiple values relation from two excel columns

I have excel file with two columns: After data import I have the following list: ...
2 votes
5 answers
255 views

Subsequences with distinct values

(this question was modified after initial answers) For a sequence x = {6,4,2,4,2,4,6} y = Subsequences[x] gives the list of ...
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3 votes
2 answers
116 views

Determining the run length of elements in a list that satisfy a pattern

Is there a simple way to determine the run length of elements in a list that satisfy a pattern? For example, consider the following list: ...
3 votes
2 answers
187 views

How to insert a list in the second argument of Table?

I wrote the following table: k = 4; T = Table[{a[n], 0, 1}, {n, 1, k}] Which generates: ...
  • 5,061
5 votes
1 answer
77 views

Isolating sequences from a list based on a formula

SeedRandom[4]; alist = RandomInteger[{-4, 4}, 100] From this list, I can isolate similar neighbors of length two: ...
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5 votes
3 answers
226 views

Selective deletions from a list

i have two lists of strings with unequal numbers of subelements in each. i would like to remove from lis2 all instances where a pattern in lis1 appears in lis2: ...
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2 votes
2 answers
173 views

Trouble understanding function composition?

I made the following code: Cs = {{0, 1}}; f[x_] := (Clear[s]; s = (x[[2]] - x[[1]])/3; Splice[{{x[[1]], x[[1]] + s}, {x[[1]] + 2 s, x[[2]]}}]) Observe that we can ...
  • 5,061
0 votes
0 answers
46 views

How to find the sequence function $f(n,x)$ of the three given functions?

I have the three functions $f(2,x)$, $f(3,x)$ and $f(4,x)$ where $x>0$ ...
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2 votes
2 answers
153 views

While loop not working problem [closed]

I am new to Mathematica ,and I am trying to implement this while loop which adds all odd Fibonacci numbers less than or equal to 2 million but it keeps outputting 0 for sum. Any solutions for that? ...
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0 votes
0 answers
40 views

Problem with FindGeneratingFunction

I have a lengthy function of a real parameter $n$ that generates values $val$ for each $n$ {$n$, $val$}: ...
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6 votes
2 answers
173 views

Longest common subset sequence with gaps

I would like to find the longest common subset (including a gap of x) within two lists. Example: A = AAABBBBCCCCC B = CCCBBBAAABABA We can use ...
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1 vote
1 answer
108 views

RSolve unable to solve the equation

I gave the following code as input: RSolve[x[n + 1] == 1/2 x[n] + 2 Log[x[n]], x[n], n] Mathematica gave the same output: ...
0 votes
0 answers
59 views

Is there a concise way to generate a continuous less-than relationship?

Actually, I have a ton of variables, Let me simplify it to 4 in this post. vars = {a, b, c, d}; 0 < Less @@ vars < 10 0 < (a < b < c < d) < ...
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0 votes
1 answer
80 views

How to solve this RecurrenceTable in Mathematica

I would appreciate if somebody could help me with the following problem: Q: How to define this in Mathematica. ...
  • 259
0 votes
1 answer
131 views

Variable dimension tables with variable ranges

I need to construct a table that has variable dimension and variable ranges (see for tables with variable dimensions and constant ranges, e.g., this question). Suppose there is a list ...
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3 votes
1 answer
86 views

A possible issue in combination of the Infix operator ~ with Sequence [closed]

There are other similar questions on this site about using the Infix operator for more than two arguments, which I have read. But there is one thing that I wasn't able to understand and couldn't ...
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0 votes
0 answers
66 views

FindSequenceFunction with very small numbers

I need some help with FindSequenceFunction because at the moment it seems like a black box to me. For example, it deals with ...
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5 votes
1 answer
100 views

Patterns are not Sequences are not Lists, or: Global Function Argument Reversal

H[z_] := z /. {F[p__] -> F[Reverse[p]]} F[{x, y}] + F[{x, z}] + F[{}] // H Almost. It gives an annoying "Nonatomic Reverse" error message at the ...
2 votes
1 answer
79 views

Defining function with arguments in a specific pattern similar to Graphics[]

I'm trying to define a function that is of this form: ...
2 votes
0 answers
99 views

Finding recurrence relation from an inexact numerical sequence

Consider the recurrence relationship d[0] = 0; d[i_] := (1 + Sqrt[1 + 4 d[i - 1]^2])/2 /; i >= 1 which generates the following sequence (generated by using <...
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1 vote
0 answers
32 views

What subsequences does SequenceReplace consider

Consider SequenceReplace[{a, b, x, x, a, c}, {a, e_} :> e]. What subsequences does SequenceReplace consider? The ...
0 votes
1 answer
64 views

Using :> vs -> in SequenceReplace

The first example on the page for SequenceReplace is the following: SequenceReplace[{a, b, x, x, a, c}, {a, e_} :> e] ...
1 vote
1 answer
144 views

Extract function argument sequence

Is it somehow possible to access and reference the sequence of arguments of a non-pure function? For example if I want to take the derivative with respect to the n'th argument, a pseudocode example ...
4 votes
1 answer
172 views

Find the longest sequence of "1" in a SubList

I'm trying to return the sublist(s) with the longest sequence of 1, although my code is working in a majority of cases, there are exceptions that I don't understand . Example: ...
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7 votes
4 answers
398 views

Find the longest sequence of "1" in a matrix row, and its position

I would like to find the longest sequence of "1" (consecutive ones) in rows of a matrix; moreover, I would like to know the position of this sequence in the matrix . Example: Input : ...
  • 189
3 votes
1 answer
74 views

How to Map over a BlankSequence? [closed]

I would like to replace any function f[x, y, ...] in a certain expression with the same function with all its arguments squared, i.e. ...
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4 votes
1 answer
80 views

SequenceSplit around empty sequences is inconsistent

Bug introduced in 11.3 and persisting through 12.3 Only the first one recognizes a zero-length sequence between non-X's. ...
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4 votes
1 answer
64 views

Conditionally add an element to a list by using Apply to delay the Sequence until evaluation

Could you explain the details for the following code? foo[x_, y_] := {a, If[x === y, b, Sequence @@ {}]} foo[s, s] foo[s, t] Output: ...
2 votes
2 answers
148 views

Calculating Average Price and P&L Efficiently Without Loops

A very common task is stock portfolio evaluation is to calculate the average price of stock holdings for a sequence of trades and from there to calculate the (realized) profit or loss. Obviously one ...
1 vote
1 answer
197 views

check a sequence in Pi

I read that the string 36541622473 occurs in π(pi) at position 36541622473, counting from ...
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2 votes
1 answer
36 views

ordered set inclusion

Suppose I have a ordered set $A=\{2,3\}$ and $B=\{2,3,4\}$ and $C=\{2,4,3\}$. Is there any mathematica command whether $A\subset B$ gives true(or 1) but $A$ which is not a subset of $C$ gives false(or ...
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0 votes
1 answer
80 views

Why won't Sequence work when wrapping a list of arguments for deletion with Remove?

I wrote a quick and dirty little function freshStart which does a variety of things meant to give me a nearly fresh Kernel without having to ...
  • 2,337
2 votes
1 answer
198 views

How can I get an element of a sequence?

How can I get an element of a sequence? For example Sequence[a,b,c,d] How can get c?
  • 2,293
1 vote
0 answers
92 views

Alternatives not working with Sequence[]?

In the following piece of code I've specified two possibilities to match via Alternatives, but only one of them seems to be considered: ...
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1 vote
2 answers
111 views

Recursive sequence with RecurenceTable

I want to compute elements of a recursive sequence and use them as coefficients of a power series. However, the (i+1)-th element depends on all previous elements. Writing this as a sum in ...
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1 vote
1 answer
44 views

Using For to generate a sequence

I want to find the smallest positive integer $k$ such that the finite list s[k*m] contains no odd numbers, for $m=1,2 \dots$. Unfortunately ...
2 votes
2 answers
110 views

Use Mathematica to split a sequence according to other two sequences

I want to use Mathematica to solve the following problem: For example I have a sequence 101. I want to compare it with $1101$ and $0101$. The comparison has the following procedure: Check the first ...
1 vote
0 answers
62 views

Avoiding the memory requirements of an accumulation of returned Nulls (etc)

There is an extensive but relatively old answer to a similar question here, and there are many Qs and As about avoiding using Table where possible. My problem is a mixture of the two: I have been ...
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4 votes
2 answers
151 views

Generate a sequence of sequences

Imagine I have a sequence of M integers each of which is either zero or one. How do I generate a sequence of all such 2^M sequences?
1 vote
2 answers
127 views

How to use a general method to solve this problem

Suppose $a_{n}>0(n=1,2,\cdots)$. The series $ \sum_{n=1}^{\infty} a_{n}$ converges and the constant $ \lambda \in\left(0, \frac{\pi}{2}\right)$. Now I need to judge whether the series $\sum_{n=1}^{\...
2 votes
2 answers
186 views

How to judge whether the series is absolutely convergent?

I need to judge whether the series $\sum_{n=1}^{\infty}(-1)^{n}\left(1-\cos \frac{\alpha}{n}\right)$ (α>0) is absolutely convergent. ...