a(n) = (5*n^2 + 5*n - 6)/2.

Terms

a(0) =2a(1) =12a(2) =27a(3) =47a(4) =72a(5) =102a(6) =137a(7) =177a(8) =222a(9) =272a(10) =327a(11) =387a(12) =452a(13) =522a(14) =597a(15) =677a(16) =762a(17) =852a(18) =947a(19) =1047a(20) =1152a(21) =1262a(22) =1377a(23) =1497a(24) =1622a(25) =1752a(26) =1887a(27) =2027a(28) =2172a(29) =2322