0
$\begingroup$

I am trying to find a formula for the $n$th term of a sequence of rational numbers less than 1. Regardless of how many terms I include in the table, FindSequenceFunction copies the input as the output. Perhaps my sequence is too complicated, but I would like to know if there are any other methods or functions which help find the $n$th term of a sequence.

Here's the code for the sorted table: 

sopf[n_] := Plus @@ (First /@ FactorInteger[n])
Composite[n_Integer] := FixedPoint[n + PrimePi[#] + 1 &, n]
Sort[Table[
1 - ((1 + sopf[Composite[j]] - PrimeNu[Composite[j]])/
Composite[j]), {j, 1, 30}]]

With output

*{1/3, 2/5, 3/7, 5/11, 6/13, 8/17, 9/19, 1/2, 8/15, 4/7, 20/33, 8/13,
2/3, 2/3, 24/35, 7/10, 5/7, 8/11, 11/15, 3/4, 16/21, 7/9, 4/5, 5/6,
38/45, 17/20, 7/8, 8/9, 8/9, 15/16}*
Improve this question
$\endgroup$
4
  • $\begingroup$ try oeis.org perhaps $\endgroup$
    – pdmclean
    Oct 21, 2017 at 22:00
  • $\begingroup$ @pdmclean that only works for integers. $\endgroup$
    – The Substitute
    Oct 21, 2017 at 22:26
  • 1
    $\begingroup$ Yes, but you can search the sequence of numerators and the sequence of denominators separately. $\endgroup$
    – J. M.'s eventual burnout ♦
    Oct 26, 2017 at 13:11
  • $\begingroup$ I tried, they didn't match any sequence in their database. $\endgroup$
    – The Substitute
    Oct 27, 2017 at 1:58

1 Answer 1

Reset to default
1
$\begingroup$

This is how to answer any stupid question about finite sequences in pre-employment testing:

a = Sort[RandomInteger[{1, 100}, 20]];
f = Interpolation[a];
Show[
 ListPlot[a],
 Plot[f[t], {t, 1, Length[a]}]
 ]
Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.