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A296679
Expansion of e.g.f. arcsinh(arctanh(x)) (odd powers only).
5
1, 1, 13, 341, 18649, 1599849, 205524837, 36391450941, 8546308276401, 2564025898856913, 957697868873929149, 435619128300038521893, 237104370189582892175241, 152148421079949399306125625, 113672892845152570858515803925, 97820056722556900357454981990925
OFFSET
0,3
FORMULA
E.g.f.: arcsin(arctan(x)) (odd powers only, absolute values).
E.g.f.: log((log(1 + x) - log(1 - x))/2 + sqrt(1 + (log(1 + x) - log(1 - x))^2/4)) (odd powers only).
EXAMPLE
arcsinh(arctanh(x)) = x/1! + x^3/3! + 13*x^5/5! + 341*x^7/7! + 18649*x^9/9! + 1599849*x^11/11! + ...
MATHEMATICA
nmax = 16; Table[(CoefficientList[Series[ArcSinh[ArcTanh[x]], {x, 0, 2 nmax + 1}], x] Range[0, 2 nmax + 1]!)[[n]], {n, 2, 2 nmax, 2}]
nmax = 16; Table[(CoefficientList[Series[Log[(Log[1 + x] - Log[1 - x])/2 + Sqrt[1 + (Log[1 + x] - Log[1 - x])^2/4]], {x, 0, 2 nmax + 1}], x] Range[0, 2 nmax + 1]!)[[n]], {n, 2, 2 nmax, 2}]
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Dec 18 2017
STATUS
approved