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A119042
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Numbers k such that the k-th triangular number contains only digits {0,1,6}.
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2
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1, 3, 4, 11, 36, 141, 179, 363, 1095, 3633, 4473, 4704, 36333, 44758, 46079, 46904, 57620, 1414920, 1460141, 4474371, 14560288, 348310541, 1822424761720, 34670191840011, 471172177895936, 4472359691719799
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OFFSET
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1,2
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COMMENTS
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Next term exceeds 1.4*10^16.
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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, 6}] == {} &] (* Vincenzo Librandi, Dec 25 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, 6]]; // Vincenzo Librandi, Dec 25 2015
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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STATUS
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approved
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