a(n) = n! with trailing zeros omitted.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =12a(6) =72a(7) =504a(8) =4032a(9) =36288a(10) =36288a(11) =399168a(12) =4790016a(13) =62270208a(14) =871782912a(15) =1307674368a(16) =20922789888a(17) =355687428096