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

Author

Clark Kimberling

Keywords

• nonn

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

Extensions

More terms from Sean A. Irvine, Jul 10 2019