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A012956
arctanh(tan(x)+arcsin(x))=2*x+19/3!*x^3+1033/5!*x^5+139697/7!*x^7...
0
2, 19, 1033, 139697, 35245537, 14290318777, 8497769039329, 6967293521417777, 7532911599857139777, 10384169309400234051945, 17776358796209666513666881, 36997487367543781033857758881
OFFSET
0,1
FORMULA
a(n) ~ (2*n)! / r^(2*n+1), where r = 0.4711468334470747286400957442399130911292... is the root of the equation tan(r)+arcsin(r) = 1. - Vaclav Kotesovec, Feb 05 2015
MATHEMATICA
nn = 20; Table[(CoefficientList[Series[ArcTanh[ArcSin[x] + Tan[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 05 2015 *)
CROSSREFS
Sequence in context: A165937 A128345 A013052 * A012976 A013107 A369946
KEYWORD
nonn
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved