a(n) = (n!+4)/4.

Terms

a(0) =7a(1) =31a(2) =181a(3) =1261a(4) =10081a(5) =90721a(6) =907201a(7) =9979201a(8) =119750401a(9) =1556755201a(10) =21794572801a(11) =326918592001