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A137108
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Numbers k such that k and k^2 use only the digits 2, 4, 7 and 9.
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0
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OFFSET
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1,1
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COMMENTS
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Generated with DrScheme.
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LINKS
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EXAMPLE
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499979277^2 = 249979277429442729.
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MATHEMATICA
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okQ[n_]:=Module[{id=Union[IntegerDigits[n^2]]}, And@@Table[MemberQ[ {2, 4, 7, 9}, id[[i]]], {i, Length[id]}]]; Flatten[Table[Select[ FromDigits/@ Tuples[{2, 4, 7, 9}, d], okQ], {d, 10}]] (* Harvey P. Dale, Jun 26 2012 *)
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CROSSREFS
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KEYWORD
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base,nonn,changed
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AUTHOR
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Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008
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STATUS
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approved
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