A119154 Triangular numbers composed of digits {2,3,6}.

3, 6, 36, 66, 666, 22366, 333336, 23232336, 336662326, 2232222336, 3263633236, 6266233326, 262322266326, 266633626626, 2263263223266, 36226633633326, 66333362366236266, 3236622262232626626666, 3322222636222323322336, 2332636666226262326336266

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A058458, A119155. See A119033 for a table of cross-references.

Programs

Mathematica

Select[Flatten[Table[FromDigits/@Tuples[{2,3,6},n],{n,10}]],OddQ[Sqrt[8#+1]]&] (* The program generates the first 12 terms of the sequence. To generate more, increase the constant after "n," but the program will take longer to run. *) (* Harvey P. Dale, Apr 18 2020 *)

Formula

a(n) = A000217(A119155(n)). - Tyler Busby, Mar 28 2023

Extensions

a(20) from Tyler Busby, Mar 28 2023