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A119112 Numbers n such that the n-th triangular number contains only digits {1,3,4}. 2
1, 2, 53, 258, 25746, 53746, 161946, 7930238, 14927378, 29810546, 4714751561, 25742623453 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Next entry must be greater than 1.4*10^16.

LINKS

Table of n, a(n) for n=1..12.

G. 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 * A109791 A265441 A119777

Adjacent sequences:  A119109 A119110 A119111 * A119113 A119114 A119115

KEYWORD

nonn,base,more

AUTHOR

Giovanni Resta, May 10 2006

STATUS

approved

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Last modified January 22 07:39 EST 2020. Contains 331139 sequences. (Running on oeis4.)