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A119112
Numbers k such that the k-th triangular number contains only digits {1,3,4}.
2
1, 2, 53, 258, 25746, 53746, 161946, 7930238, 14927378, 29810546, 4714751561, 25742623453, 94268917816334704578
OFFSET
1,2
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
KEYWORD
nonn,base,more
AUTHOR
Giovanni Resta, May 10 2006
EXTENSIONS
a(13) from Tyler Busby, Mar 30 2023
STATUS
approved