a(n) = (8*n+3)^4.

Terms

a(0) =81a(1) =14641a(2) =130321a(3) =531441a(4) =1500625a(5) =3418801a(6) =6765201a(7) =12117361a(8) =20151121a(9) =31640625a(10) =47458321a(11) =68574961a(12) =96059601a(13) =131079601a(14) =174900625a(15) =228886641a(16) =294499921a(17) =373301041a(18) =466948881a(19) =577200625