A119122 Numbers k such that the k-th triangular number contains only digits {1,3,9}.

1, 2, 13, 621, 4458, 489884458, 632318261, 893464178, 16684802253, 1621069592578, 2502478528946, 250255842662341, 1543458022195053, 527851115257700546

Offset

1,2

Links

Table of n, a(n) for n=1..14.

G. Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A119121. See A119034 for a table of cross-references.

Sequence in context: A013111 A179434 A101342 * A109947 A175513 A064185

Adjacent sequences: A119119 A119120 A119121 * A119123 A119124 A119125

Keyword

nonn,base,more

Author

Giovanni Resta, May 10 2006

Extensions

a(14) from Max Alekseyev, Oct 14 2012

Status

approved