A119099 Triangular numbers composed of digits {1,2,4}.

1, 21, 2211, 222111, 1422141, 4244241, 22221111, 44241121, 124212441, 2222211111, 222222111111, 22222221111111, 1111114242224421, 2222222211111111, 21414424114444221, 222222222111111111, 1144211112222224221, 22222222221111111111, 44241214122411121441

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers

Crossrefs

Cf. A000217, A053881, A119100. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119100(n)). - Michel Marcus, Mar 19 2023

Extensions

a(17)-a(19) from Tyler Busby, Mar 18 2023