[ exp(11/15)*n! ].

Terms

a(0) =2a(1) =4a(2) =12a(3) =49a(4) =249a(5) =1499a(6) =10493a(7) =83946a(8) =755519a(9) =7555194a(10) =83107140a(11) =997285682a(12) =12964713872a(13) =181505994212