A119052 Numbers k such that the k-th triangular number contains only digits {0,2,5}.

10, 100, 224, 714, 1000, 10000, 32410, 67089, 100000, 210010, 1000000, 1019825, 2100010, 2109599, 3231100, 10000000, 21000010, 33173785, 71450010, 100000000, 200101000, 201000100, 210000010, 663702049, 1000000000

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• G. Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A119051. See A119034 for a table of cross-references.

Programs

Magma

[n: n in [1..2*10^7] | Set(Intseq(Binomial(n+1, 2))) subset [0, 2, 5]]; // Vincenzo Librandi, Oct 07 2015

Mathematica

Select[Range[2 10^7], Complement[IntegerDigits[Binomial[# + 1, 2]], {0, 2, 5}] == {}&] (* Vincenzo Librandi, Oct 07 2015 *)