A009244 Expansion of e.g.f.: exp(tan(x))/cos(x).

1, 1, 2, 6, 20, 92, 448, 2688, 17296, 127312, 1013600, 8850336, 83547584, 845380928, 9196867072, 105911556096, 1301697829120, 16814357324032, 230093807905280, 3294279618252288, 49636887216382976

Offset: 0

Author

R. H. Hardin

Keywords

• nonn
• easy

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 0..477
• P. Barry, Constructing Exponential Riordan Arrays from Their A and Z Sequences, Journal of Integer Sequences, 17 (2014), #14.2.6.

Programs

Mathematica

With[{nn=30},CoefficientList[Series[Exp[Tan[x]]/Cos[x],{x,0,nn}],x] Range[ 0,nn]!] (* Harvey P. Dale, Jun 06 2014 *)

Extensions

Extended and signs tested by Olivier Gérard, Mar 15 1997

Prior Mathematica program replaced and definition clarified by Harvey P. Dale, Jun 06 2014