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A119046
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Numbers k such that the k-th triangular number contains only digits {0,1,8}.
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2
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1, 4, 46, 126, 141, 404, 466, 1541, 4004, 4195, 4666, 12658, 13266, 40004, 41995, 46666, 147024, 400004, 402760, 466666, 1272798, 1327266, 1332666, 4000004, 4666666, 40000004, 46666666, 133272666, 133326666, 148329375, 400000004
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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, 8}] == {} &] (* Vincenzo Librandi, Dec 25 2015 *)
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PROG
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(Magma) [n: n in [1..4*10^6] | Set(Intseq(Binomial(n+1, 2))) subset [0, 1, 8]]; // Vincenzo Librandi, Dec 25 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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