A119130 Triangular numbers composed of digits {1,4,9}.

1, 91, 49141, 144991, 94414411, 941194191, 1194944941, 491919414441, 9999119991411411, 4149449911949149941, 11144994144991949991, 191444491991911949911, 144949944191119411441191, 9449441991199141999494149499499111914141

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A006716, A119131. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119131(n)). - Tyler Busby, Mar 31 2023

Extensions

a(14) from Max Alekseyev, Aug 15 2013