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A009294
Expansion of e.g.f.: exp(x)/cosh(log(1+x)).
1
1, 1, 0, 1, 1, -9, 46, -125, -279, 7021, -57644, 247941, 829225, -30119309, 346210866, -2030635529, -9055135439, 430103734425, -6356431497464, 47224459865161, 263232787214961, -15445025103197969, 278983778423699350
OFFSET
0,6
FORMULA
a(n) ~ n! * sqrt(2) * cos(1-(3*n-1)*(Pi/4)) / (2^(n/2) * exp(1)). - Vaclav Kotesovec, Jan 24 2015
MATHEMATICA
With[{nn=30}, CoefficientList[Series[Exp[x]/Cosh[Log[1+x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Aug 27 2013 *)
CoefficientList[Series[(2*E^x*(1 + x))/(1 + (1 + x)^2), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *)
CROSSREFS
Sequence in context: A117052 A356424 A280852 * A061620 A260513 A001781
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
Definition clarified and prior Mathematica program replaced by Harvey P. Dale, Aug 27 2013
STATUS
approved