[ exp(21/22)*n! ].

Terms

a(0) =2a(1) =5a(2) =15a(3) =62a(4) =311a(5) =1870a(6) =13091a(7) =104730a(8) =942577a(9) =9425770a(10) =103683474a(11) =1244201692a(12) =16174622000a(13) =226444708001