a(n) = 7*n^2 + n.

Terms

a(0) =0a(1) =8a(2) =30a(3) =66a(4) =116a(5) =180a(6) =258a(7) =350a(8) =456a(9) =576a(10) =710a(11) =858a(12) =1020a(13) =1196a(14) =1386a(15) =1590a(16) =1808a(17) =2040a(18) =2286a(19) =2546a(20) =2820a(21) =3108a(22) =3410a(23) =3726a(24) =4056a(25) =4400a(26) =4758a(27) =5130a(28) =5516a(29) =5916