[ exp(3/22)*n! ].

Terms

a(0) =1a(1) =2a(2) =6a(3) =27a(4) =137a(5) =825a(6) =5776a(7) =46210a(8) =415896a(9) =4158962a(10) =45748587a(11) =548983054a(12) =7136779702a(13) =99914915833