Concentric 19-gonal numbers.

Terms

a(0) =0a(1) =1a(2) =19a(3) =39a(4) =76a(5) =115a(6) =171a(7) =229a(8) =304a(9) =381a(10) =475a(11) =571a(12) =684a(13) =799a(14) =931a(15) =1065a(16) =1216a(17) =1369a(18) =1539a(19) =1711a(20) =1900a(21) =2091a(22) =2299a(23) =2509a(24) =2736a(25) =2965a(26) =3211a(27) =3459a(28) =3724a(29) =3991