a(n) = (2*n+1)^4.

Terms

a(0) =1a(1) =81a(2) =625a(3) =2401a(4) =6561a(5) =14641a(6) =28561a(7) =50625a(8) =83521a(9) =130321a(10) =194481a(11) =279841a(12) =390625a(13) =531441a(14) =707281a(15) =923521a(16) =1185921a(17) =1500625a(18) =1874161a(19) =2313441a(20) =2825761a(21) =3418801a(22) =4100625a(23) =4879681a(24) =5764801a(25) =6765201a(26) =7890481a(27) =9150625a(28) =10556001a(29) =12117361