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A009597
Expansion of sinh(sinh(log(1+x))).
1
0, 1, -1, 4, -18, 106, -750, 6196, -58408, 617716, -7234020, 92842696, -1294948776, 19493497024, -314874396928, 5430592728016, -99578626460160, 1934092698170896, -39660351268817808, 856128235903319296
OFFSET
0,4
LINKS
FORMULA
a(n) ~ n! * (-1)^(n+1) * exp(1/4 + sqrt(2*n)) / (2^(9/4) * n^(3/4) * sqrt(Pi)). - Vaclav Kotesovec, Jan 24 2015
MATHEMATICA
Sinh[ Sinh[ Log[ 1+x ] ] ]
CoefficientList[Series[Sinh[(x*(2 + x))/(2*(1 + x))], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *)
PROG
(PARI) x='x+O('x^50); concat([0], Vec(serlaplace(sinh(sinh(log(1+x)))))) \\ G. C. Greubel, Apr 11 2017
CROSSREFS
Sequence in context: A020114 A376110 A354015 * A241841 A241842 A306003
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved