Subdiagonal of array of n-gonal numbers A081422.

Terms

a(0) =1a(1) =3a(2) =12a(3) =34a(4) =75a(5) =141a(6) =238a(7) =372a(8) =549a(9) =775a(10) =1056a(11) =1398a(12) =1807a(13) =2289a(14) =2850a(15) =3496a(16) =4233a(17) =5067a(18) =6004a(19) =7050a(20) =8211a(21) =9493a(22) =10902a(23) =12444a(24) =14125a(25) =15951a(26) =17928a(27) =20062a(28) =22359a(29) =24825