Triangular numbers for which the sum of the digits is an octagonal number.

Terms

a(0) =0a(1) =1a(2) =10a(3) =1596a(4) =2775a(5) =3486a(6) =3828a(7) =4278a(8) =4656a(9) =5565a(10) =6555a(11) =7626a(12) =8256a(13) =9453a(14) =14196a(15) =15753a(16) =16653a(17) =17391a(18) =18336a(19) =21945a(20) =22791a(21) =23871a(22) =24753a(23) =28920a(24) =32385a(25) =34716a(26) =37128a(27) =38226a(28) =39621a(29) =40755