A119144 Triangular numbers composed of digits {1,6,9}.

1, 6, 66, 91, 666, 961191, 996166, 1191196, 96111966961, 99119996661, 16161696119661, 196999111911966, 661969169911666, 11961669169169616, 19961691661699161, 991961666199161911, 6116119911196616916, 16961161696691611916961, 911666691991111199916696

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A053911, A119145. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119145(n)). - Michel Marcus, Mar 24 2023

Extensions

a(18)-a(19) from Tyler Busby, Mar 24 2023