a(n) = (n^3 - n^2)*6^n.

Terms

a(0) =0a(1) =144a(2) =3888a(3) =62208a(4) =777600a(5) =8398080a(6) =82301184a(7) =752467968a(8) =6530347008a(9) =54419558400a(10) =438984437760