login
Expansion of tan(sin(x)^2)/2.
3

%I #20 Apr 02 2017 15:32:07

%S 0,1,-4,136,-6784,524416,-64036864,10501374976,-2283962220544,

%T 634741960278016,-218778649767706624,91736006502034702336,

%U -45959204407743090786304,27112425203442398670094336,-18603328214677391682184413184,14689562944237012958430694998016

%N Expansion of tan(sin(x)^2)/2.

%H Alois P. Heinz, <a href="/A024264/b024264.txt">Table of n, a(n) for n = 0..100</a>

%F a(n) = (2*n)! * [x^(2*n)] tan(sin(x)^2)/2.

%F a(n) ~ (2*n)! * (-1)^(n+1) / (sqrt(Pi*(2+Pi)) * (log(sqrt(Pi/2) + sqrt(1 + Pi/2)))^(2*n+1)). - _Vaclav Kotesovec_, Feb 04 2015

%t With[{nn=30},Take[CoefficientList[Series[Tan[Sin[x]^2]/2,{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Jan 30 2013 *)

%Y Cf. A009675.

%K sign

%O 0,3

%A _R. H. Hardin_

%E Extended with signs Mar 1997