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A119105
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Triangular numbers composed of digits {1,2,7}.
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2
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1, 21, 171, 1711, 2211, 72771, 121771, 222111, 712221, 22221111, 72222171, 2222211111, 12177127711, 72177771711, 171277217121, 222222111111, 22222221111111, 121727717277211, 2222222211111111, 22117121117271271, 222222222111111111, 12172172111271712221
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OFFSET
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1,2
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LINKS
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FORMULA
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MATHEMATICA
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Flatten[Table[Select[FromDigits/@Tuples[{1, 2, 7}, n], OddQ[Sqrt[8#+1]]&], {n, 17}]] (* Harvey P. Dale, Sep 02 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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EXTENSIONS
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STATUS
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approved
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