a(n) = (9*n + 2)^4.

Terms

a(0) =16a(1) =14641a(2) =160000a(3) =707281a(4) =2085136a(5) =4879681a(6) =9834496a(7) =17850625a(8) =29986576a(9) =47458321a(10) =71639296a(11) =104060401a(12) =146410000a(13) =200533921a(14) =268435456a(15) =352275361a(16) =454371856a(17) =577200625a(18) =723394816a(19) =895745041a(20) =1097199376a(21) =1330863361a(22) =1600000000a(23) =1908029761a(24) =2258530576a(25) =2655237841