Numbers k such that the k-th triangular number contains only digits {0,4,5}.

Terms

a(0) =9a(1) =10a(2) =89a(3) =100a(4) =899a(5) =900a(6) =1000a(7) =8989a(8) =9000a(9) =10000a(10) =30134a(11) =31624a(12) =90000a(13) =95289a(14) =100000a(15) =900000a(16) =953944a(17) =1000000a(18) =9000000a(19) =10000000a(20) =10044944a(21) =32880100a(22) =90000000a(23) =100000000a(24) =900000000a(25) =1000000000a(26) =3328800100a(27) =9000000000