OFFSET
0,2
FORMULA
a(n) ~ exp(n + 1) * n^(2*n - 1/2) / sqrt(2*Pi).
MATHEMATICA
Table[SeriesCoefficient[Product[(1 + k*x)^n / (1 - k*x)^n, {k, 1, n}], {x, 0, n}], {n, 0, 20}]
PROG
(PARI) a(n) = my(x='x+O(x^(n+1))); polcoef(prod(k=1, n, (1+k*x)^n/ (1-k*x)^n), n); \\ Michel Marcus, Feb 19 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Feb 18 2022
STATUS
approved