[ exp(13/18)*n! ].

Terms

a(0) =2a(1) =4a(2) =12a(3) =49a(4) =247a(5) =1482a(6) =10377a(7) =83019a(8) =747171a(9) =7471712a(10) =82188838a(11) =986266063a(12) =12821458831a(13) =179500423635