A119127 Numbers k such that the k-th triangular number contains only digits {1,4,7}.

1, 18, 38, 58, 15306, 28893, 3851686, 595216169886, 53248694146381, 536869582203620058, 14927275335718688666

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base
• more

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A079654. See A119034 for a table of cross-references.

Extensions

a(10)-a(11) from Tyler Busby, Mar 31 2023