A218399 Triangular numbers composed of digits {0,4,7}.

40470, 4744740, 4770740040, 44747000047470770470774700707404004740

Offset

1,1

Comments

a(5) > 10^40.

Links

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

Giovanni Resta, Tridigital Triangular Numbers.

Formula

a(n) = A000217(A218400(n)).

Crossrefs

Cf. A000217, A218400. See A119033 for a table of cross-references.

Sequence in context: A216291 A216290 A237970 * A090060 A250955 A334004

Adjacent sequences: A218396 A218397 A218398 * A218400 A218401 A218402

Keyword

base,nonn,more

Author

Max Alekseyev, Oct 28 2012

Status

approved