a(n) = n*8^(n-1).

Terms

a(0) =0a(1) =1a(2) =16a(3) =192a(4) =2048a(5) =20480a(6) =196608a(7) =1835008a(8) =16777216a(9) =150994944a(10) =1342177280a(11) =11811160064a(12) =103079215104a(13) =893353197568