a(n) = n^3*3^(n-1).

Terms

a(0) =0a(1) =1a(2) =24a(3) =243a(4) =1728a(5) =10125a(6) =52488a(7) =250047a(8) =1119744a(9) =4782969a(10) =19683000a(11) =78594219a(12) =306110016a(13) =1167575877a(14) =4374822312a(15) =16142520375a(16) =58773123072a(17) =211488540273a(18) =753145430616