A119071 Triangular numbers composed of digits {0,4,5}.

45, 55, 4005, 5050, 404550, 405450, 500500, 40405555, 40504500, 50005000, 454044045, 500054500, 4050045000, 4540044405, 5000050000, 405000450000, 455005054540, 500000500000, 40500004500000, 50000005000000, 50450455004040, 540550504445050, 4050000045000000

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A058436, A119072. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119072(n)). - Michel Marcus, Mar 15 2023

Extensions

a(21)-a(23) from Tyler Busby, Mar 14 2023