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A009130
Expansion of e.g.f. cosh(log(1+x))/cos(x).
1
1, 0, 2, -3, 23, -90, 676, -4305, 37533, -325332, 3366166, -36472095, 443702291, -5732993838, 80707226328, -1207617980205, 19365202513145, -328878787017000, 5925189947339626, -112532916285619515, 2251485624038961615
OFFSET
0,3
LINKS
FORMULA
a(n) ~ n! * (-1)^n * sin(1) / sin(2). - Vaclav Kotesovec, Jan 22 2015
MATHEMATICA
CoefficientList[Series[((1 + (1 + x)^2)*Sec[x])/(2*(1 + x)), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 22 2015 *)
With[{nn=20}, CoefficientList[Series[Cosh[Log[1+x]]/Cos[x], {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, Aug 21 2021 *)
PROG
(PARI) x='x+O('x^30); Vec(serlaplace(cosh(log(1+x))/cos(x))) \\ G. C. Greubel, Jul 28 2018
(Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Cosh(Log(1+x))/Cos(x))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jul 28 2018
CROSSREFS
Sequence in context: A350523 A262730 A260127 * A093504 A370279 A009180
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved