A053893 -id:A053893 - cp's OEIS frontend

A119115 Triangular numbers composed of digits {1,3,6}.

1, 3, 6, 36, 66, 136, 666, 13366, 333336, 6631661361, 113113613161, 663363661366, 16116313316131, 633161111666331, 633613661136316, 1331116613613361, 33311633636366361, 663661636336331361, 61163111131316636331, 6313111611636313666666, 1616111661666616161331131

Offset: 1

Giovanni Resta, May 10 2006

Giovanni Resta, Tridigital Triangular Numbers

Cf. A000217, A053893, A119116. See A119033 for a table of cross-references.

Table[Select[FromDigits/@Tuples[{1,3,6},n],OddQ[Sqrt[8#+1]]&],{n,18}]//Flatten (* Harvey P. Dale, Sep 18 2017 *)

a(n) = A000217(A119116(n)). - Michel Marcus, Mar 22 2023

a(19)-a(21) from Tyler Busby, Mar 22 2023

A053892 Numbers k such that k^2 contains only digits {1,3,6}.

Original entry on oeis.org

1, 4, 6, 19, 56, 369, 796, 1146, 1156, 3656, 8131, 19056, 40204, 81619, 258131, 5624381, 24762131, 362789631, 1079982019, 11666754546, 562726517354, 3337114272296, 5624644998854, 18266544874814631, 11537606482136410218512760694

Offset: 1

Patrick De Geest, Mar 15 2000

Patrick De Geest, Squares containing at most three distinct digits, Index entries for related sequences
H. Mishima Squares consisted of 3 different digits [From _Max Alekseyev_, May 30 2009]

Cf. A053893.

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 04 2005
Two more terms from Jon E. Schoenfield, Sep 03 2006
One more term from Mishima's webpage added by Max Alekseyev, May 30 2009
a(25) from Zhao Hui Du, Mar 09 2024

cp's OEIS Frontend

A119115 Triangular numbers composed of digits {1,3,6}.

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