a(n) = (3*n+1)^4.

Terms

a(0) =1a(1) =256a(2) =2401a(3) =10000a(4) =28561a(5) =65536a(6) =130321a(7) =234256a(8) =390625a(9) =614656a(10) =923521a(11) =1336336a(12) =1874161a(13) =2560000a(14) =3418801a(15) =4477456a(16) =5764801a(17) =7311616a(18) =9150625a(19) =11316496a(20) =13845841a(21) =16777216a(22) =20151121a(23) =24010000a(24) =28398241a(25) =33362176a(26) =38950081a(27) =45212176a(28) =52200625a(29) =59969536