Expansion of e.g.f. (1/2)*(x^2*exp(x))*(cosh(x))^2.

Terms

a(0) =0a(1) =0a(2) =1a(3) =3a(4) =18a(5) =70a(6) =315a(7) =1281a(8) =5124a(9) =19692a(10) =73845a(11) =270655a(12) =974358a(13) =3454386a(14) =12090351a(15) =41851005a(16) =143489160a(17) =487862872a(18) =1646537193a(19) =5520742011a(20) =18402473370a(21) =61018727070a(22) =201361799331a(23) =661617340153