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A009751
Expansion of e.g.f. tan(x)*tan(tanh(x)), even powers only.
2
0, 2, 8, 48, 2176, 72704, 2567168, 320538624, 23648567296, 2869964963840, 550752408829952, 81617924549246976, 20769854695130791936, 5449382125873097867264, 1599364150040158382587904, 573113440182309263706685440, 238664184536900397410937733120
OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..240 (terms 0..100 from Vincenzo Librandi)
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Tan[x]*Tan[Tanh[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Feb 07 2014 *)
PROG
(PARI) x='x+O('x^50); v=Vec(serlaplace(tan(x)*tan(tanh(x)))); concat([0], vector(#v\2, n, v[2*n-1])) \\ G. C. Greubel, Feb 12 2018
CROSSREFS
Sequence in context: A009741 A322309 A009745 * A356658 A279239 A279109
KEYWORD
nonn
AUTHOR
EXTENSIONS
Extended and signs tested by Olivier Gérard, Mar 15 1997
Prior Mathematica program replaced by and one more term from Harvey P. Dale, Feb 07 2014
STATUS
approved