Questions tagged [integer-sequence]

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47
votes
8answers
2k views

Is it possible to invoke the OEIS from Mathematica?

I had always wondered if there might be a way to write a function, which I'll call OEISData[], that more or less works as a curated data function for The On-Line ...
24
votes
3answers
565 views

Speeding up the built-in Rudin-Shapiro and Thue-Morse sequence functions

Version 10.2 introduced two well-studied sequences as functions: the (Golay-)Rudin-Shapiro sequence (RudinShapiro[]) and the (Prouhet-)Thue-Morse sequence (...
20
votes
4answers
925 views

Generate and graph the Recamán Sequence

I was surprised to see that we don't have any posts that mention the Recamán Sequence, so I figured I should post it as a challenge. By definition, $a_0=0$ and $a_n=a_{n-1}-n$ if the r.h.s. is ...
20
votes
3answers
829 views

Partitioning a number into consecutive integers

Consider n=45; then $$1+2+3+4+5+6+7+8+9=45$$ $$5+6+7+8+9+10=45$$ $$7+8+9+10+11=45$$ $$14+15+16=45$$ $$22+23=45$$ Question: how to find all representations of a ...
14
votes
10answers
5k views

Fibonacci Sequence Generator

I'm trying to write a function in Workbench which will generate a Fibonacci sequence starting with F0 = 0 and F1 = 1. So far I ...
11
votes
4answers
3k views

How to implement recursive function

I'm trying to do the following (taken from an answer by Watson to my question on Math SE): Start with $x_1=2$, say. Then define $$x_{n+1} = |\{i \in \{1,\dots,n-1\} \;:\; x_i=x_n\}|$$ i.e. number ...
11
votes
3answers
4k views

Easier program for period of Fibonacci sequence modulo p

For a little project I need to calculate the period of a Fibonacci sequence modulo p, for which p is a prime number. For example, the Fibonacci sequence modulo 19 would be: $$0, 1, 1, 2, 3, 5, 8, 13, ...
11
votes
2answers
305 views

Animating a growing ListPlot

I stumbled upon this (rather contrived but interesting) integer sequence. As it exhibits quite different behaviour at different scales, I would like to generate an animated ...
11
votes
0answers
224 views

Find sequence of sequences?

There is a function FindSequenceFunction in Mathematica, that can identify a sequence of integers based on a few first elements. But what if I have a set of finite ...
10
votes
9answers
3k views

How can I make a Tribonacci sequence in the form of a list?

How can I make a Tribonacci sequence that is in listing form? it suppose to look like the Fibonacci sequence but I couldn't get ...
10
votes
1answer
158 views

How do I expand StirlingS2[n, 10] in terms of elementary functions?

I know that it is possible to expand StirlingS2[n, 10] in terms of elementary functions of n. I tried ...
9
votes
5answers
15k views

How to detect if a sequence of integers is consecutive

I'm not a math-guy really (a programmer actually) and this is my first question. And excuse me if I can not explain my problem good. The problem is I have a sequence of integers and I want to detect ...
9
votes
2answers
664 views

How to construct rectangular figures from the Fibonacci numbers?

How do you construct rectangular figures using the Fibonacci numbers in Mathematica using graphics? I know that the basis of the construction of these figures are the formulae for summing the terms, ...
9
votes
5answers
655 views

How to tell Mathematica to do this with decimal part of real number?

My apologies if this was asked here before. My friend and I want to do this: Suppose that we have some real number $a. a_1 a_2...a_n...$ where $a_i$ are digits in the set $\{1,2,3,4,5,6,7,8,9,0\}$ (...
8
votes
5answers
285 views

Return last number in sub-sequences in a list of integers

Given a list of integers like this: z = {113, 117, 118, 119, 120, 121, 475, 476, 529, 538, 542, 543, 544} I want a function that returns: ...
8
votes
2answers
1k views

Finding the coefficient of a certain power in a generating function

I want to compute $(t^1+\dots +t^5)(t^2+\dots+ t^6)(t^3+\dots +t^9)$ and find the coefficient of $t^{15}$ for example. $t$ is an indeterminate Now in Maple this is simply as ...
8
votes
3answers
4k views

Is there a relatively quick way to solve my integer-valued equation?

This is a very simple problem. It can be solved by nested Forloops that exhaustively test every possible case, throwing out all non-solutions. Find all the ...
7
votes
2answers
655 views

Finding large Collatz Sequences, trying to improve speed

Background: I am already very much in love with Mathematica but I am also a novice. So far I have only gathered experience in procedural programming in Python. Generally speaking I am trying to ...
6
votes
4answers
834 views

RandomInteger with equal number of 1 and -1

I want to generate a list of random integers with only three values 1,0,-1. I know it can be done through RandomInteger[{-1, 1}, n]. How can I impose constraint on this list so that every integers in ...
6
votes
3answers
310 views

Find the number of $n$ such that $n!$ is a sum of three squares

I want to check the following theorem by using Mathematica: $\textbf{Theorem} $. $\text{The estimate}$ $\# \{n \le x:n! \text{ is a sum of three squares}\}=7x/8+O(x^{2/3})$ $\text{holds.}$...
6
votes
1answer
103 views

Are there different Method options that can be used with FindSequenceFunction?

The help page states that Method is an option to use with FindSequenceFunction, but I don't find any further information. (There ...
6
votes
2answers
92 views

Selecting integers which are not a member in an ordered list of integers

I have an ordered list of integers, i.e.: list = {1,3,5,6,8,10,12,15}; and I want to know if there is a fast way to get a list of the integers that do not appear ...
6
votes
1answer
151 views

Find subsequence A in sequence B A007908 - OEIS

I have sequence A as A007908 - OEIS and pattern B which is a sub-sequence of that sequence A. I need to find index of first occurrence of the given pattern. For example pattern ..1010... I've looked ...
5
votes
3answers
111 views

How to find a list of values of recurrence equation?

I tried with RSolve,but it fails: RSolve[{x[n + 1] == n + Sum[j*x[j], {j, 1, n}], x[1] == 1}, x[n], n] Returns unevaluated ...
5
votes
1answer
57 views

The next element can be obtained using Predict or SequencePredict?

I want to estimate the next number with the data of the sequence listed as elements 0 and 1. For example, when data = {0,0,1,1,0,0,1,0,0,1,1,0,0,1} (actually, ...
5
votes
1answer
241 views

More efficient Omnibus number determination?

Amusing myself with concepts from "Omnibus Sequences, Coupon Collection, and Missing Word Counts", in particular the sequences. To paraphrase the concept, a string is k-Omni over some alphabet a if ...
4
votes
2answers
975 views

How to plot the Fibonacci convergence to the golden ratio?

I am interested to plot a convergence result of the Fibonacci sequence, namely $\frac{F(n+1)}{F(n)}\rightarrow\phi$ as $n\rightarrow\infty$. So far I have created the following plot: So, I am ...
4
votes
3answers
395 views

Opposite Collatz Conjecture

I'm trying to explore what would happen if you change the collatz conjecture to flip the equations for odds and evens. So if you have an even number you multiply by 3, add 1, and divide by 2. If you ...
3
votes
1answer
531 views

Evaluate large Fibonacci numbers

I want to evaluate that Fibonacci[28143753246]. However the result is OverFlow[]. Is there any way to evaluate it? Thank you.
3
votes
4answers
469 views

Print all numbers from a sequence which don't contain the digit 7

so i have this: Cases[RecurrenceTable[{a[n + 1] == 7 a[n] + n, a[1] == 1}, a, {n, 7}], Except[7]] But i noticed that it will only exclude numbers that are 7, and ...
3
votes
2answers
99 views

How do I determine the 15th Lucas term in the 3rd order?

I want to implement the Lucas n-Step Number. This command taken from here doesn't seem to work, am I using the right command? ...
3
votes
1answer
59 views

FindGeneratingFunction gives up too easily [closed]

I am trying to automatically find a generating function from the coefficients of a simple rational function using Mathematica's FindGeneratingFunction: ...
3
votes
1answer
576 views

Using IntegerPartitions for distinct integers

What I would like to do is to find a way to test how many ways m distinct integers from the set {1,..., n} where ...
3
votes
1answer
530 views

How can I get the general term of this recurrence equations?

Following is the recurrence relation: a[1] = 1; a[n_] := a[n - a[n - 1]] + 1 Array[a, 28] I tried to use RSolve, but it doesn'...
3
votes
1answer
149 views

How many terms does FindSequenceFunction need to discover a simple polynomial rule?

Consider a simple sequence starting with seq1 = {429, 1014, 1935, 3264, 5073, 7434, 10419, 14100, 18549, 23838}; We are looking for a rule (of course there ...
3
votes
1answer
83 views

how to obtain these increasing integers for given n and m?

Let n and m be natural numbers. Then, how does one write a function ordint[n,m] that gives ...
3
votes
1answer
113 views

The permutation of given number sequence that has specific correlation with another

I am interested in the relationship between the Pearson correlation coefficients and the permutations of two random number sequences. An initial Mathematica study is as below: ...
3
votes
1answer
211 views

Interpreting a formula from Graph Theory - where do x and y come from?

I'm trying to understand the generating function for OEIS A062734, which is in Mathematica. Essentially, despite knowing no Mathematica at all, I think I can parse most of it, but where do $x$ and $y$ ...
3
votes
1answer
97 views

Guess Diophantine equation from its solutions

Take for example the equation $$ n^2=x^2+y^2+1 $$ where $x,y$ are integers. This equation admits solutions only for some values of $n$, to wit, $$ n=1,3,9,17,19,33,35,51,73,81,99,\dots $$ Can we ...
3
votes
0answers
55 views

Prepending a sequence with zeros gives `FindGeneratingFunction` hard time

Asking for FindGeneratingFunction[{1, 3, 11, 43, 171, 683, 2731, 10923, 43691, 174763}, t] gives the answer (namely ...
2
votes
2answers
176 views

Engel expansion

How do I do an Engel expansion in Mathematica? And find the unique non-decreasing sequence of positive integers $ \{ a_1 ,a_2,a_3,\dots \}$ , such $$\frac{e}{\pi}=\frac{1}{a_1}+\frac{1}{a_1 a_2}+\...
2
votes
2answers
387 views

splitting integer problem

I want to cut the integer into small numbers and show me all the possibilities. For example, if I choose integer 6, then I would like to know how many combination of a 5 dimensional vector (or table ?)...
2
votes
2answers
192 views

Building a sequence of the digits of π

Just for fun, I'm trying to write up some code that will list a finite number of the digits of pi, i.e. {3,1,4,1,5,...,#}. I have the general pattern, but for some ...
2
votes
2answers
87 views

Producing a particular sequence of integers recursively [closed]

I am supposed to write a function which computes the next integer in a sequence from the given one. For example: nextval[57] should give mm ...
2
votes
1answer
117 views

Constructing the following figure using mathematica

How do I construct the figure in the image using the formulae in Mathematica? I defined the following functions for the 4 cases. Can you also explain the significance of these in relation to the ...
2
votes
1answer
113 views

efficiently method for generating a sequence

The sequence is defined as $a(1)=1,a(n)=a(n-1)+a\left(\left\lfloor \log _2(n)\right\rfloor \right)$ A natural way do this is ...
2
votes
3answers
143 views

Finding the largest palindrome which is the product of two 2-digit numbers

My goal is to find the largest palindrome which is the product of two 2-digit numbers using the following program. I want the program to add each palindrome it finds, to the list H. I also want it to ...
2
votes
1answer
97 views

FindInstance skips solutions

I have an equation to compute the bit-error rate of a binary symmetric channel: $$P_{err}(n,p) = \sum_{k = \frac{n-1}{2} + 1}^n\binom n k p^k(1-p)^{n-k}$$ I then want to find the smallest $n$-...
2
votes
2answers
92 views

Mathematica analog to Wolfram|Alpha dataset analysis [closed]

I have a set of sequences with length 8,48,480,5760,.. and would like to do sequence analysis on them. I plugged the length 8 sequence into wolframalpha: https://www.wolframalpha.com/input/?i=11,+2,+...
2
votes
1answer
98 views

Unexpected behavior of FindGeneratingFunction

FindGeneratingFunction will give up to computer sometimes?Such as FindGeneratingFunction[{1, 4, 6, 4, 1}, x] But actually the ...