OFFSET
0,2
COMMENTS
See A220412 for definitions and references.
MATHEMATICA
F[0, _] = 1; F[n_, x_] := F[n, x] = -2x Sum[Binomial[n-1, 2k+1] BernoulliB[2k+2]/(2k+2) F[n-2k-2, x], {k, 0, n/2-1}] // Expand;
a[n_] := (-1)^n Denominator[Together[F[2n, x]]];
Table[a[n], {n, 0, 21}] (* Jean-François Alcover, Jun 27 2019 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Peter Luschny, Dec 30 2012
STATUS
approved