OFFSET
1,3
FORMULA
E.g.f.: Sum_{k>=1} A067856(k) * log(1 + arctan(x^k)) / k.
MATHEMATICA
b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[c[i], j] b[n - i j, i - 1], {j, 0, n/i}]]]; c[n_] := c[n] = {1, 0, -1, 0}[[Mod[n, 4, 1]]]/n - b[n, n - 1]; a[n_] := n! c[n]; Table[a[n], {n, 1, 23}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, May 22 2022
STATUS
approved