A119047 Triangular numbers composed of digits {0,1,9}.

1, 10, 91, 190, 990, 10011, 19110, 19900, 90100, 1911990, 1991010, 1999000, 99991011, 199110990, 199910010, 199990000, 901999101, 1000900911, 1111019091, 19991100990, 19999100010, 19999900000, 1999911000990, 1999991000010, 1999999000000, 11109109109010

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A119048. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119048(n)). - Michel Marcus, Mar 14 2023

Extensions

a(24)-a(26) from Tyler Busby, Mar 14 2023