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A119036
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Numbers k such that the k-th triangular number contains only digits {0,1,3}.
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2
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1, 2, 4, 24, 77, 141, 778, 1421, 1435, 1620, 14220, 15035, 45453, 148533, 148546, 249122, 471404, 791597, 4497399, 2580747997, 47180737658, 148411814220, 244989930458, 447283652733, 1422190795997, 2581981034024
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Select[Range[2 10^7], Complement[IntegerDigits[Binomial[# + 1, 2]], {0, 1, 3}] == {}&] (* Vincenzo Librandi, Oct 07 2015 *)
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PROG
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(Magma) [n: n in [1..2*10^7] | Set(Intseq(Binomial(n+1, 2))) subset [0, 1, 3]]; // Vincenzo Librandi, Oct 07 2015
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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