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 A024229 Expansion of e.g.f.: tanh(x)*sin(tan(x))/2 (even part). 2

%I #24 Sep 17 2022 13:39:32

%S 0,1,-2,19,-1572,-24763,-5174758,-230357353,-45947071688,

%T -3138700558071,-787255563055690,-40961532387015781,

%U -13644908739614623724,5015831039379054245197,1910018990150165668013778,1856616739480127236630886175,892801482776535024911075390576

%N Expansion of e.g.f.: tanh(x)*sin(tan(x))/2 (even part).

%H Stefano Spezia, <a href="/A024229/b024229.txt">Table of n, a(n) for n = 0..200</a>

%t nmax=200; expan=Series[Tanh[x]*Sin[Tan[x]]/2, {x, 0, 2*nmax}]; Join[{0}, Table[(2n)! Coefficient[expan, x^(2n)], {n, nmax}]] (* _Stefano Spezia_, Sep 17 2022 *)

%o (PARI) my(x='x+O('x^50), v=Vec(serlaplace(tanh(x)*sin(tan(x))/2))); concat(0, vector(#v\2, k, v[2*k-1])) \\ _Michel Marcus_, Sep 17 2022

%Y Cf. A009834.

%K sign

%O 0,3

%A _R. H. Hardin_

%E Extended with signs, Mar 1997

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Last modified August 14 18:55 EDT 2024. Contains 375166 sequences. (Running on oeis4.)