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A009244 Expansion of e.g.f.: exp(tan(x))/cos(x). 1
1, 1, 2, 6, 20, 92, 448, 2688, 17296, 127312, 1013600, 8850336, 83547584, 845380928, 9196867072, 105911556096, 1301697829120, 16814357324032, 230093807905280, 3294279618252288, 49636887216382976 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..20.

P. Barry, Constructing Exponential Riordan Arrays from Their A and Z Sequences, Journal of Integer Sequences, 17 (2014), #14.2.6.

MATHEMATICA

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

CROSSREFS

Sequence in context: A027315 A005965 A000421 * A104985 A210690 A079575

Adjacent sequences:  A009241 A009242 A009243 * A009245 A009246 A009247

KEYWORD

nonn,easy

AUTHOR

R. H. Hardin

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

STATUS

approved

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Last modified November 12 16:50 EST 2018. Contains 317116 sequences. (Running on oeis4.)