a(n) = 2*n^2 + 3*n - 1.

Terms

a(0) =4a(1) =13a(2) =26a(3) =43a(4) =64a(5) =89a(6) =118a(7) =151a(8) =188a(9) =229a(10) =274a(11) =323a(12) =376a(13) =433a(14) =494a(15) =559a(16) =628a(17) =701a(18) =778a(19) =859a(20) =944a(21) =1033a(22) =1126a(23) =1223a(24) =1324a(25) =1429a(26) =1538a(27) =1651a(28) =1768a(29) =1889