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A119052
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Numbers k such that the k-th triangular number contains only digits {0,2,5}.
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3
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10, 100, 224, 714, 1000, 10000, 32410, 67089, 100000, 210010, 1000000, 1019825, 2100010, 2109599, 3231100, 10000000, 21000010, 33173785, 71450010, 100000000, 200101000, 201000100, 210000010, 663702049, 1000000000
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OFFSET
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1,1
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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, 2, 5}] == {}&] (* 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, 2, 5]]; // 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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