A272656 Bisection of A003319: a(n) = A003319(2n).

1, 1, 13, 461, 29093, 2829325, 392743957, 73943424413, 18176728317413, 5661698774848621, 2181096921557783605, 1018705098450570562877, 567347013156626397484421, 371514945708955154128328461, 282629242654284555347577144277, 247210800978211588125067686948317

Offset: 0

Author

N. J. A. Sloane, May 15 2016

Keywords

• nonn

Links

• Michael De Vlieger, Table of n, a(n) for n = 0..224 (a(n) for n = 1..200 from Vincenzo Librandi)

Crossrefs

Cf. A003319, A272657.

Programs

Mathematica

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

Extensions

a(0) = 1 set by Peter Luschny, Aug 03 2022