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%I #18 Sep 08 2022 08:44:37
%S 1,0,0,-3,7,-30,194,-1365,10893,-98028,980324,-10783575,129402835,
%T -1682236842,23551315878,-353269738185,5652315810841,-96089368784280,
%U 1729608638117192,-32862564124226667,657251282484533151
%N Expansion of e.g.f. cosh(log(1+x))*cos(x).
%H G. C. Greubel, <a href="/A009128/b009128.txt">Table of n, a(n) for n = 0..250</a>
%F a(n) ~ n! * (-1)^n * cos(1) / 2. - _Vaclav Kotesovec_, Jan 22 2015
%t CoefficientList[Series[((1 + (1 + x)^2)*Cos[x])/(2*(1 + x)), {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 22 2015 *)
%o (PARI) x='x+O('x^30); Vec(serlaplace(cosh(log(1+x))*cos(x))) \\ _G. C. Greubel_, Jul 28 2018
%o (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
%K sign,easy
%O 0,4
%A _R. H. Hardin_
%E Extended with signs by _Olivier Gérard_, Mar 15 1997
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