a(n) = (n-1)*(4*n+1).

Terms

a(0) =0a(1) =9a(2) =26a(3) =51a(4) =84a(5) =125a(6) =174a(7) =231a(8) =296a(9) =369a(10) =450a(11) =539a(12) =636a(13) =741a(14) =854a(15) =975a(16) =1104a(17) =1241a(18) =1386a(19) =1539a(20) =1700a(21) =1869a(22) =2046a(23) =2231a(24) =2424a(25) =2625a(26) =2834a(27) =3051a(28) =3276a(29) =3509