Numbers k such that the k-th triangular number contains only digits {0,2,5}.

Terms

a(0) =10a(1) =100a(2) =224a(3) =714a(4) =1000a(5) =10000a(6) =32410a(7) =67089a(8) =100000a(9) =210010a(10) =1000000a(11) =1019825a(12) =2100010a(13) =2109599a(14) =3231100a(15) =10000000a(16) =21000010a(17) =33173785a(18) =71450010a(19) =100000000a(20) =200101000a(21) =201000100a(22) =210000010a(23) =663702049a(24) =1000000000