Generalized centered polygonal numbers.

Terms

a(0) =0a(1) =1a(2) =6a(3) =22a(4) =62a(5) =147a(6) =308a(7) =588a(8) =1044a(9) =1749a(10) =2794a(11) =4290a(12) =6370a(13) =9191a(14) =12936a(15) =17816a(16) =24072a(17) =31977a(18) =41838a(19) =53998a(20) =68838a(21) =86779a(22) =108284a(23) =133860a(24) =164060a(25) =199485a(26) =240786a(27) =288666a(28) =343882a(29) =407247