a(n) = (12*n + 1)^4.

Terms

a(0) =1a(1) =28561a(2) =390625a(3) =1874161a(4) =5764801a(5) =13845841a(6) =28398241a(7) =52200625a(8) =88529281a(9) =141158161a(10) =214358881a(11) =312900721a(12) =442050625a(13) =607573201a(14) =815730721a(15) =1073283121a(16) =1387488001a(17) =1766100625a(18) =2217373921a(19) =2750058481a(20) =3373402561a(21) =4097152081a(22) =4931550625a(23) =5887339441a(24) =6975757441a(25) =8208541201