a(n) = (5n + 3)^4.

Terms

a(0) =81a(1) =4096a(2) =28561a(3) =104976a(4) =279841a(5) =614656a(6) =1185921a(7) =2085136a(8) =3418801a(9) =5308416a(10) =7890481a(11) =11316496a(12) =15752961a(13) =21381376a(14) =28398241a(15) =37015056a(16) =47458321a(17) =59969536a(18) =74805201a(19) =92236816a(20) =112550881a(21) =136048896