a(n) = (10*n+7)^4.

Terms

a(0) =2401a(1) =83521a(2) =531441a(3) =1874161a(4) =4879681a(5) =10556001a(6) =20151121a(7) =35153041a(8) =57289761a(9) =88529281a(10) =131079601a(11) =187388721a(12) =260144641a(13) =352275361a(14) =466948881a(15) =607573201a(16) =777796321a(17) =981506241a(18) =1222830961a(19) =1506138481