a(n) = 3*n*(3*n + 7)/2 + 4.

Terms

a(0) =4a(1) =19a(2) =43a(3) =76a(4) =118a(5) =169a(6) =229a(7) =298a(8) =376a(9) =463a(10) =559a(11) =664a(12) =778a(13) =901a(14) =1033a(15) =1174a(16) =1324a(17) =1483a(18) =1651a(19) =1828a(20) =2014a(21) =2209a(22) =2413a(23) =2626a(24) =2848a(25) =3079a(26) =3319a(27) =3568a(28) =3826a(29) =4093