[ exp(9/20)*n! ].

Terms

a(0) =1a(1) =3a(2) =9a(3) =37a(4) =188a(5) =1129a(6) =7904a(7) =63234a(8) =569109a(9) =5691091a(10) =62602003a(11) =751224046a(12) =9765912599a(13) =136722776399