26-gonal numbers: a(n) = n*(12*n-11).

Terms

a(0) =0a(1) =1a(2) =26a(3) =75a(4) =148a(5) =245a(6) =366a(7) =511a(8) =680a(9) =873a(10) =1090a(11) =1331a(12) =1596a(13) =1885a(14) =2198a(15) =2535a(16) =2896a(17) =3281a(18) =3690a(19) =4123a(20) =4580a(21) =5061a(22) =5566a(23) =6095a(24) =6648a(25) =7225a(26) =7826a(27) =8451a(28) =9100a(29) =9773