a(n) = (3*n + 1)*n!.

Terms

a(0) =1a(1) =4a(2) =14a(3) =60a(4) =312a(5) =1920a(6) =13680a(7) =110880a(8) =1008000a(9) =10160640a(10) =112492800a(11) =1357171200a(12) =17723059200a(13) =249080832000