A119150 Triangular numbers composed of digits {1,8,9}.

1, 91, 1891, 8911, 188191, 889111, 899811, 998991, 1188111, 11899881, 88891111, 1918188891, 8888911111, 9998888991, 189889118191, 191819818191, 199198198891, 888889111111, 88888891111111, 8888888911111111, 888888889111111111, 88888888891111111111

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A053915, A119151. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119151(n)). - Michel Marcus, Mar 24 2023

Extensions

a(21)-a(22) from Tyler Busby, Mar 24 2023