OFFSET
0,6
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..5000
FORMULA
a(5*n) = A022597(n). a(n) = 0 unless n == 0 (mod 5). - Michael Somos, Jun 08 2012
MATHEMATICA
A022597[n_] := SeriesCoefficient[ Product[1 + q^k, {k, n}]^-2, {q, 0, n}]; a[n_] := If[Mod[n, 5] != 0, 0, A022597[n/5]]; a[0] = 1; Table[a[n], {n, 0, 96}] (* Jean-François Alcover, Nov 12 2012, after Michael Somos *)
PROG
(PARI) x='x+O(x^100); Vec(prod(k=1, 20, (1-x^(10*k-5))^2)) \\ G. C. Greubel, Oct 20 2018
(Magma) m:=100; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!( (&*[(1-x^(10*k-5))^2: k in [1..20]]))); // G. C. Greubel, Oct 20 2018
CROSSREFS
KEYWORD
sign
AUTHOR
Eric W. Weisstein, Nov 12 2003
STATUS
approved