OFFSET
0,3
FORMULA
a(n) ~ c * d^n * n!^2 / n^(3/2), where d = 52.447924272991536496097233490380538810534457762204101802471270109895148... and c = 0.028365099209561232079163758339093959048662789595134609351298413762... - Vaclav Kotesovec, Oct 16 2021
MATHEMATICA
Table[SeriesCoefficient[Product[1/(1 - (2*k-1)^2*x), {k, 1, n}], {x, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Oct 16 2021 *)
PROG
(PARI) a(n) = polcoef(1/prod(k=1, n, 1-(2*k-1)^2*x+x*O(x^n)), n);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 28 2021
STATUS
approved