A119186 Triangular numbers composed of digits {3,5,6}.

3, 6, 36, 55, 66, 666, 3655, 5356, 5565, 6555, 333336, 3635556, 5656566, 35536665, 56365653, 56663335, 63365653, 655636366, 53533355655, 55663663653, 533533653555, 555533363556, 6653355565366, 555665666566566, 35356355566555653, 653366333366663536656

Offset

1,1

Links

Table of n, a(n) for n=1..26.

Giovanni Resta, Tridigital Triangular Numbers

Formula

a(n) = A000217(A119187(n)). - Tyler Busby, Mar 24 2023

Mathematica

Table[Select[FromDigits/@Tuples[{3, 5, 6}, n], OddQ[Sqrt[8#+1]]&], {n, 15}]//Flatten (* Harvey P. Dale, Aug 03 2021 *)

Crossrefs

Cf. A000217, A053945, A119187. See A119033 for a table of cross-references.

Sequence in context: A130317 A019467 A106128 * A119115 A079653 A119063

Adjacent sequences: A119183 A119184 A119185 * A119187 A119188 A119189

Keyword

nonn,base

Author

Giovanni Resta, May 10 2006

Extensions

a(25)-a(26) from Tyler Busby, Mar 24 2023

Status

approved