E.g.f.: 1/(1+x^2 - 2*x*cosh(x)).

Terms

a(0) =1a(1) =2a(2) =6a(3) =30a(4) =216a(5) =1930a(6) =20400a(7) =251174a(8) =3541888a(9) =56226258a(10) =991514880a(11) =19230159982a(12) =406873353216