a(n) = (9*n^2 + 13*n + 6)/2.

Terms

a(0) =3a(1) =14a(2) =34a(3) =63a(4) =101a(5) =148a(6) =204a(7) =269a(8) =343a(9) =426a(10) =518a(11) =619a(12) =729a(13) =848a(14) =976a(15) =1113a(16) =1259a(17) =1414a(18) =1578a(19) =1751a(20) =1933a(21) =2124a(22) =2324a(23) =2533a(24) =2751a(25) =2978a(26) =3214a(27) =3459a(28) =3713a(29) =3976