a(n) = (5*n + 1)^7.

Terms

a(0) =1a(1) =279936a(2) =19487171a(3) =268435456a(4) =1801088541a(5) =8031810176a(6) =27512614111a(7) =78364164096a(8) =194754273881a(9) =435817657216a(10) =897410677851