A088129 Expansion of e.g.f. sinh(x)/(1-x)^2.
0, 1, 4, 19, 104, 661, 4812, 39607, 364240, 3704617, 41310740, 501328411, 6578864184, 92843236669, 1402257345244, 22570640656831, 385718738160032, 6975222838783057, 133078088319220260, 2671441145266564387, 56287972249358876680, 1242089553461115778021
Offset: 0
Programs
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Mathematica
nmax=21; CoefficientList[Series[Sinh[x]/(1-x)^2, {x,0,nmax}], x]Range[0,nmax]! (* Stefano Spezia, Jan 15 2024 *)
Formula
a(n) = Sum_{k=0..floor((n-1)/2)} binomial(n,2*k+1) * (n-2*k)!. - Ilya Gutkovskiy, Apr 10 2022
Comments