[ exp(6/19)*n! ].

Terms

a(0) =1a(1) =2a(2) =8a(3) =32a(4) =164a(5) =987a(6) =6911a(7) =55292a(8) =497632a(9) =4976324a(10) =54739565a(11) =656874783a(12) =8539372179a(13) =119551210518