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A012388
arcsin(tan(x)*tan(x))=2/2!*x^2+16/4!*x^4+392/6!*x^6+21376/8!*x^8...
1
0, 2, 16, 392, 21376, 2117792, 333550336, 76433892992, 23981418704896, 9862199971860992, 5144452992189485056, 3317894031273853601792, 2591931617534673513250816, 2411532576645611695219515392
OFFSET
0,2
FORMULA
a(n) ~ 2^(4*n-1) * (2*n)! / (n^(3/2) * Pi^(2*n)). - Vaclav Kotesovec, Feb 08 2015
MATHEMATICA
nn = 20; Table[(CoefficientList[Series[ArcSin[Tan[x]^2], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Feb 08 2015 *)
CROSSREFS
Sequence in context: A295710 A012390 A009613 * A297368 A012752 A188904
KEYWORD
nonn
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
a(0)=0 prepended by Vaclav Kotesovec, Feb 08 2015
STATUS
approved