A012771 - OEIS

%I #8 Nov 01 2013 10:05:32

%S 1,1,1,3,9,25,105,371,1393,11985,71025,-13981,-898887,45127017,

%T 455252889,-5553908333,-75822681503,1415759895841,21366754787169,

%U -404022487469117,-7036035942040855,148035510590478137

%N exp(cosh(x)*arcsinh(x))=1+x+1/2!*x^2+3/3!*x^3+9/4!*x^4+25/5!*x^5...

%F E.g.f.: (x+sqrt(1+x^2))^(cosh(x)). - _Vaclav Kotesovec_, Nov 01 2013

%F a(n) ~ 2*cos(1) * sin(Pi/2*(n-cos(1))) * n^(n-1) / exp(n). - _Vaclav Kotesovec_, Nov 01 2013

%t CoefficientList[Series[Exp[Cosh[x]*ArcSinh[x]], {x, 0, 20}], x]* Range[0, 20]! (* _Vaclav Kotesovec_, Nov 01 2013 *)

%K sign

%O 0,4

%A Patrick Demichel (patrick.demichel(AT)hp.com)