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

1,2

Links

Table of n, a(n) for n=1..19.

Giovanni Resta, Tridigital Triangular Numbers

Formula

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

Crossrefs

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

Sequence in context: A369097 A219104 A219983 * A319170 A359223 A215160

Adjacent sequences: A119096 A119097 A119098 * A119100 A119101 A119102

Keyword

nonn,base

Author

Giovanni Resta, May 10 2006

Extensions

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

Status

approved