a(0)=0, a(n) = (a(n-1) XOR n) * n.

Terms

a(0) =0a(1) =1a(2) =6a(3) =15a(4) =44a(5) =205a(6) =1218a(7) =8547a(8) =68440a(9) =615897a(10) =6158910a(11) =67747911a(12) =812974980a(13) =10568674805a(14) =147961447354