[ exp(2/19)*n! ].

Terms

a(0) =1a(1) =2a(2) =6a(3) =26a(4) =133a(5) =799a(6) =5599a(7) =44795a(8) =403160a(9) =4031607a(10) =44347682a(11) =532172186a(12) =6918238422a(13) =96855337921