[ exp(17/18)*n! ].

Terms

a(0) =2a(1) =5a(2) =15a(3) =61a(4) =308a(5) =1851a(6) =12959a(7) =103678a(8) =933103a(9) =9331039a(10) =102641438a(11) =1231697258a(12) =16012064360a(13) =224168901043