a(n) = 4*n^2 - 7*n + 4.

Terms

a(0) =1a(1) =6a(2) =19a(3) =40a(4) =69a(5) =106a(6) =151a(7) =204a(8) =265a(9) =334a(10) =411a(11) =496a(12) =589a(13) =690a(14) =799a(15) =916a(16) =1041a(17) =1174a(18) =1315a(19) =1464a(20) =1621a(21) =1786a(22) =1959a(23) =2140a(24) =2329a(25) =2526a(26) =2731a(27) =2944a(28) =3165a(29) =3394