A231620 a(n) = A000930(n^2), where A000930 is Narayana's cows sequence.
1, 1, 3, 19, 277, 8641, 578949, 83316385, 25753389181, 17098272199297, 24382819596721629, 74684329652984094451, 491347682599497451569523, 6943240361573523613067995729, 210741152533202801182666172606913, 13738849457010997118546333815068560833, 1923823572225984354415961546862346889944243
Offset: 0
Keywords
Links
- G. C. Greubel, Table of n, a(n) for n = 0..75
Programs
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Mathematica
Table[SeriesCoefficient[1/(1 - x - x^3), {x, 0, n^2}], {n,0,25}] (* G. C. Greubel, Apr 26 2017 *) -
PARI
{a(n) = polcoeff(1/(1-x-x^3 + x*O(x^(n^2))), n^2)} for(n=0, 20, print1(a(n), ", "))
Formula
a(n) = [x^(n^2)] 1 / (1 - x - x^3) for n>=0.