A119224 Triangular numbers composed of digits {5,7,8}.

55, 78, 5778, 7875, 8778, 75855, 887778, 7575778, 55888878, 57775875, 87787875, 88877778, 5587777755, 8888777778, 787575878775, 888887777778, 8857787887578, 88888877777778, 5777878558877778, 8888888777777778, 555875575755575778, 888888887777777778

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A119225. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119225(n)). - Tyler Busby, Mar 26 2023

Extensions

a(21)-a(22) from Tyler Busby, Mar 26 2023