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

1,1

Links

Table of n, a(n) for n=1..8.

Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

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

Sequence in context: A042191 A042729 A156292 * A119207 A165254 A058069

Adjacent sequences: A119202 A119203 A119204 * A119206 A119207 A119208

Keyword

nonn,base,more

Author

Giovanni Resta, May 10 2006

Extensions

a(8) from Tyler Busby, Mar 31 2023

Status

approved