A119217 Numbers k such that the k-th triangular number contains only digits {4,7,8}.

12, 132, 947, 1332, 3867, 13332, 133332, 299492, 1222692, 1333332, 13333332, 133333332, 1333333332, 3944306652, 13333333332, 122020365307, 133333333332, 394329425347, 988724307827, 1333333333332, 12528986215052

Offset

1,1

Links

Table of n, a(n) for n=1..21.

G. Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A119216. See A119034 for a table of cross-references.

Sequence in context: A111085 A002721 A340508 * A358113 A334334 A119237

Adjacent sequences: A119214 A119215 A119216 * A119218 A119219 A119220

Keyword

nonn,base

Author

Giovanni Resta, May 10 2006

Status

approved