A024428 S(n,n) + S(n-1,n-2) + S(n-2,n-4) + ... + S(n-k+1,n-2k+2), where k = [ (n+1)/2 ] and S(i,j) are Stirling numbers of second kind.

1, 1, 2, 4, 8, 18, 42, 102, 260, 684, 1860, 5216, 15020, 44388, 134336, 415672, 1313696, 4234904, 13911528, 46525992, 158279872, 547327904, 1922455440, 6854491840, 24794405328, 90940138256, 338037825952, 1272862982272, 4853075024192

Offset

1,3

Links

Table of n, a(n) for n=1..29.

Formula

G.f.: Sum_{k>=0} x^k / Product_{l=1..k} (1-l*x^2). - Ralf Stephan, Apr 18 2004

G.f.: 1/x/Q(0) - 1/x where Q(k)= 1 - x/(1 - x^2*(k+1)/Q(k+1)); (continued fraction). - Sergei N. Gladkovskii, Apr 14 2013

Crossrefs

Sequence in context: A078678 A261492 A027056 * A330269 A049075 A318797

Adjacent sequences: A024425 A024426 A024427 * A024429 A024430 A024431

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from Sean A. Irvine, Jul 10 2019

Status

approved