[ exp(3/5)*n! ].

Terms

a(0) =1a(1) =3a(2) =10a(3) =43a(4) =218a(5) =1311a(6) =9183a(7) =73467a(8) =661210a(9) =6612104a(10) =72733151a(11) =872797820a(12) =11346371670a(13) =158849203381