a(n) = (3*n)^8.

Terms

a(0) =0a(1) =6561a(2) =1679616a(3) =43046721a(4) =429981696a(5) =2562890625a(6) =11019960576a(7) =37822859361a(8) =110075314176a(9) =282429536481a(10) =656100000000