A119081 Triangular numbers composed of digits {0,5,7}.

55, 5050, 7750, 70500, 500500, 50005000, 5000050000, 500000500000, 7700750050575, 50000005000000, 5000000050000000, 75075057775077570, 500000000500000000, 7550055000555057000, 50000000005000000000, 505750055750070750570, 775077070557070757070

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A119082. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119082(n)). - Michel Marcus, Mar 23 2023

Extensions

a(16)-a(17) from Tyler Busby, Mar 23 2023