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 A024297 Expansion of e.g.f. tan(x)*tan(tan(x))/2 (even powers only). 0
 0, 1, 12, 344, 18496, 1617152, 209249792, 37538874368, 8908210487296, 2699849585000448, 1017035120794927104, 466006356701359898624, 255181639297776949919744, 164564302025304936925888512 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Table of n, a(n) for n=0..13. MATHEMATICA With[{nn=30}, Take[CoefficientList[Series[Tan[x]Tan[Tan[x]]/2, {x, 0, nn}], x] Range[ 0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Mar 18 2023 *) PROG (PARI) x='x+O('x^40); v=Vec(serlaplace(tan(x)*tan(tan(x))/2)); concat([0], vector(#v\2, n, v[2*n-1])) \\ Michel Marcus, Mar 13 2019 CROSSREFS Cf. A009750. Sequence in context: A231520 A305108 A027015 * A077296 A080481 A209425 Adjacent sequences: A024294 A024295 A024296 * A024298 A024299 A024300 KEYWORD nonn AUTHOR R. H. Hardin EXTENSIONS Extended and signs tested March 1997. Name edited by Michel Marcus, Mar 13 2019 Prior Mathematica program replaced by Harvey P. Dale, Mar 18 2023 STATUS approved

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Last modified May 23 06:14 EDT 2024. Contains 372760 sequences. (Running on oeis4.)