a(n) = 3*n^2 - 4*n + 3.

Terms

a(0) =2a(1) =7a(2) =18a(3) =35a(4) =58a(5) =87a(6) =122a(7) =163a(8) =210a(9) =263a(10) =322a(11) =387a(12) =458a(13) =535a(14) =618a(15) =707a(16) =802a(17) =903a(18) =1010a(19) =1123a(20) =1242a(21) =1367a(22) =1498a(23) =1635a(24) =1778a(25) =1927a(26) =2082a(27) =2243a(28) =2410a(29) =2583