[ exp(9/23)*n! ].

Terms

a(0) =1a(1) =2a(2) =8a(3) =35a(4) =177a(5) =1064a(6) =7453a(7) =59629a(8) =536666a(9) =5366663a(10) =59033296a(11) =708399560a(12) =9209194286a(13) =128928720014