a(n) = n!*Sum_{d|n} (-1)^(d+1)/d!.

Terms

a(0) =1a(1) =1a(2) =7a(3) =11a(4) =121a(5) =479a(6) =5041a(7) =18479a(8) =423361a(9) =1844639a(10) =39916801a(11) =298710719a(12) =6227020801a(13) =43606442879