a(n) = (9*n^2 + 5*n + 2)/2.

Terms

a(0) =1a(1) =8a(2) =24a(3) =49a(4) =83a(5) =126a(6) =178a(7) =239a(8) =309a(9) =388a(10) =476a(11) =573a(12) =679a(13) =794a(14) =918a(15) =1051a(16) =1193a(17) =1344a(18) =1504a(19) =1673a(20) =1851a(21) =2038a(22) =2234a(23) =2439a(24) =2653a(25) =2876a(26) =3108a(27) =3349a(28) =3599a(29) =3858