a(0)=2, a(n) = (a(n-1) * n) OR n.

Terms

a(0) =2a(1) =3a(2) =6a(3) =19a(4) =76a(5) =381a(6) =2286a(7) =16007a(8) =128056a(9) =1152505a(10) =11525050a(11) =126775551a(12) =1521306620a(13) =19776986061a(14) =276877804862