A119205 Numbers k such that the k-th triangular number contains only digits {4,5,7}.

9, 10, 3390, 38589, 12453549, 3080826336474, 298253071929010, 33089502135135685

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base
• more

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A119204. See A119034 for a table of cross-references.

Extensions

a(8) from Tyler Busby, Mar 31 2023