A119112 Numbers k such that the k-th triangular number contains only digits {1,3,4}.

1, 2, 53, 258, 25746, 53746, 161946, 7930238, 14927378, 29810546, 4714751561, 25742623453, 94268917816334704578

Offset

1,2

Links

Table of n, a(n) for n=1..13.

Giovanni Resta, Tridigital Triangular Numbers.

Mathematica

(Sqrt[8#+1]-1)/2&/@Table[Select[FromDigits/@Tuples[{1, 3, 4}, n], OddQ[ Sqrt[ 8#+1]]&], {n, 21}]//Flatten (* Harvey P. Dale, Jul 09 2017 *)

Crossrefs

Cf. A000217, A119111. See A119034 for a table of cross-references.

Sequence in context: A123005 A281227 A142477 * A356488 A109791 A265441

Adjacent sequences: A119109 A119110 A119111 * A119113 A119114 A119115

Keyword

nonn,base,more

Author

Giovanni Resta, May 10 2006

Extensions

a(13) from Tyler Busby, Mar 30 2023

Status

approved