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arcsin(arcsin(x)*arcsin(x))=2/2!*x^2+8/4!*x^4+248/6!*x^6+11328/8!*x^8...
0

%I #7 Feb 08 2015 04:48:38

%S 0,2,8,248,11328,1091232,148080000,30317577600,8228536780800,

%T 2957031184028160,1336782441018009600,749500660718368634880,

%U 508063303148296391147520,410659058984740631962951680

%N arcsin(arcsin(x)*arcsin(x))=2/2!*x^2+8/4!*x^4+248/6!*x^6+11328/8!*x^8...

%F a(n) ~ sqrt(tan(1)) * (2*n)! / (sqrt(2*Pi) * n^(3/2) * (sin(1))^(2*n)). - _Vaclav Kotesovec_, Feb 08 2015

%t nn = 20; Table[(CoefficientList[Series[ArcSin[ArcSin[x]^2], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* _Vaclav Kotesovec_, Feb 08 2015 *)

%K nonn

%O 0,2

%A Patrick Demichel (patrick.demichel(AT)hp.com)

%E a(0)=0 prepended by _Vaclav Kotesovec_, Feb 08 2015