a(n) = (15*n^2 + 5*n + 2)/2.

Terms

a(0) =11a(1) =36a(2) =76a(3) =131a(4) =201a(5) =286a(6) =386a(7) =501a(8) =631a(9) =776a(10) =936a(11) =1111a(12) =1301a(13) =1506a(14) =1726a(15) =1961a(16) =2211a(17) =2476a(18) =2756a(19) =3051a(20) =3361a(21) =3686a(22) =4026a(23) =4381a(24) =4751a(25) =5136a(26) =5536a(27) =5951a(28) =6381a(29) =6826