a(n) = (6*n + 5)^4.

Terms

a(0) =625a(1) =14641a(2) =83521a(3) =279841a(4) =707281a(5) =1500625a(6) =2825761a(7) =4879681a(8) =7890481a(9) =12117361a(10) =17850625a(11) =25411681a(12) =35153041a(13) =47458321a(14) =62742241a(15) =81450625a(16) =104060401a(17) =131079601a(18) =163047361a(19) =200533921a(20) =244140625a(21) =294499921a(22) =352275361a(23) =418161601a(24) =492884401a(25) =577200625a(26) =671898241