A119236 Triangular numbers composed of digits {7,8,9}.

78, 8778, 887778, 88877778, 8888777778, 777887999778, 888887777778, 7798988788878, 88888877777778, 8888888777777778, 888888887777777778, 88888888877777777778, 8888888888777777777778, 78879897887889899897778, 888888888887777777777778, 88888888888877777777777778

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A058472, A119237. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119237(n)). - Michel Marcus, Mar 27 2023

Extensions

a(15)-a(16) from Tyler Busby, Mar 27 2023