A119178 Triangular numbers composed of digits {2,7,8}.

28, 78, 2278, 8778, 222778, 828828, 887778, 8272278, 22227778, 88278828, 88877778, 2222277778, 2882872278, 8882778828, 8888777778, 222222777778, 888827778828, 888887777778, 22222227777778, 88888277778828, 88888877777778, 228887828777278, 272277272227278

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A119179. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119179(n)). - Michel Marcus, Mar 22 2023

Extensions

a(21)-a(23) from Tyler Busby, Mar 22 2023