a(n) = floor( exp(5/13)*n! ).

Terms

a(0) =1a(1) =2a(2) =8a(3) =35a(4) =176a(5) =1057a(6) =7404a(7) =59232a(8) =533088a(9) =5330885a(10) =58639742a(11) =703676914a(12) =9147799886a(13) =128069198408