a(n) = 20*n^2 + 3.

Terms

a(0) =23a(1) =83a(2) =183a(3) =323a(4) =503a(5) =723a(6) =983a(7) =1283a(8) =1623a(9) =2003a(10) =2423a(11) =2883a(12) =3383a(13) =3923a(14) =4503a(15) =5123a(16) =5783a(17) =6483a(18) =7223a(19) =8003a(20) =8823a(21) =9683a(22) =10583a(23) =11523a(24) =12503a(25) =13523a(26) =14583a(27) =15683a(28) =16823a(29) =18003