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 A119135 Numbers k such that the k-th triangular number contains only digits {1,5,7}. 2
 1, 5, 10, 18, 58, 101, 149, 1050, 1885, 5925, 10114, 15173, 47226, 550594, 585005, 1049925, 1533085, 56174285, 104987349, 123053789, 1017425330, 1230586669, 1245114914, 38878044589, 101111538130, 177627538130, 4728038741701 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..27. G. Resta, Tridigital Triangular Numbers MATHEMATICA Select[Range[2 10^7], Complement[IntegerDigits[Binomial[# + 1, 2]], {1, 5, 7}] == {}&] (* Vincenzo Librandi, Oct 07 2015 *) PROG (Magma) [n: n in [1..2*10^7] | Set(Intseq(Binomial(n+1, 2))) subset [1, 5, 7]]; // Vincenzo Librandi, Oct 07 2015 CROSSREFS Cf. A000217, A119134. See A119034 for a table of cross-references. Sequence in context: A296552 A251928 A153370 * A083287 A091922 A030776 Adjacent sequences: A119132 A119133 A119134 * A119136 A119137 A119138 KEYWORD nonn,base AUTHOR Giovanni Resta, May 10 2006 STATUS approved

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Last modified June 13 22:21 EDT 2024. Contains 373391 sequences. (Running on oeis4.)