A272657 Bisection of A003319: a(n) = A003319(2n+1).

1, 3, 71, 3447, 273343, 31998903, 5201061455, 1123596277863, 311951144828863, 108355864447215063, 46066653228356851631, 23539631662517304379719, 14238556471214701698866335, 10063612905845566536549621687, 8219089293266835899526592972943, 7682002790499533568011331441585447

Offset: 0

Author

N. J. A. Sloane, May 15 2016

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200

Crossrefs

Cf. A003319, A272656.

Programs

Mathematica

(* b = A003319 *) b[0] = 0; b[n_] := b[n] = n! - Sum[k!*b[n-k], {k, 1, n-1} ]; a[n_] := b[2n + 1]; Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Feb 18 2018 *)