OFFSET
0,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..250
FORMULA
a(n) ~ n! * (exp(-1) * sin(1 + (3*n+1)*Pi/4) - exp(1) * sin(1 - (3*n+1)*Pi/4)) / 2^((n+1)/2). - Vaclav Kotesovec, Jul 28 2018
a(n)+a(n+2*p) is divisible by p for any prime p. - Mark van Hoeij, Jun 13 2019
MATHEMATICA
With[{nmax = 30}, CoefficientList[Series[Cos[x]/Cosh[Log[1 + x]], {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, Jul 26 2018 *)
PROG
(PARI) x='x+O('x^30); Vec(serlaplace(cos(x)/cosh(log(1+x)))) \\ G. C. Greubel, Jul 26 2018
(Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Cos(x)/Cosh(Log(1+x)))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jul 26 2018
CROSSREFS
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved