a(n) = 19*n^2.

Terms

a(0) =0a(1) =19a(2) =76a(3) =171a(4) =304a(5) =475a(6) =684a(7) =931a(8) =1216a(9) =1539a(10) =1900a(11) =2299a(12) =2736a(13) =3211a(14) =3724a(15) =4275a(16) =4864a(17) =5491a(18) =6156a(19) =6859a(20) =7600a(21) =8379a(22) =9196a(23) =10051a(24) =10944a(25) =11875a(26) =12844a(27) =13851a(28) =14896a(29) =15979