a(n) = (2*n)^8.

Terms

a(0) =0a(1) =256a(2) =65536a(3) =1679616a(4) =16777216a(5) =100000000a(6) =429981696a(7) =1475789056a(8) =4294967296a(9) =11019960576a(10) =25600000000a(11) =54875873536a(12) =110075314176a(13) =208827064576a(14) =377801998336a(15) =656100000000