A218400 Numbers k such that the k-th triangular number contains only digits {0,4,7}.

284, 3080, 97680, 9460126854061817544

Offset

1,1

Comments

No other terms below 1.4*10^20.

Links

Table of n, a(n) for n=1..4.

G. Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A218399. See A119034 for a table of cross-references.

Sequence in context: A143191 A180220 A108110 * A196893 A280808 A285892

Adjacent sequences: A218397 A218398 A218399 * A218401 A218402 A218403

Keyword

base,nonn,more

Author

Max Alekseyev, Oct 28 2012

Status

approved