a(n) = n^6 + 6n.

Terms

a(0) =0a(1) =7a(2) =76a(3) =747a(4) =4120a(5) =15655a(6) =46692a(7) =117691a(8) =262192a(9) =531495a(10) =1000060a(11) =1771627a(12) =2986056a(13) =4826887a(14) =7529620a(15) =11390715a(16) =16777312a(17) =24137671a(18) =34012332a(19) =47045995a(20) =64000120a(21) =85766247a(22) =113380036a(23) =148036027a(24) =191103120a(25) =244140775a(26) =308915932