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A137145
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Numbers k such that k and k^2 use only the digits 4, 6, 7, 8 and 9.
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1
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7, 8, 67, 88, 667, 864, 886, 887, 974, 6667, 8874, 8887, 66667, 68474, 86478, 87664, 94788, 94867, 98978, 666667, 947886, 947887, 948678, 984878, 988878, 988887, 6666667, 6846886, 6974788, 6974867, 6977664, 9469788, 9478764, 9897978, 9984878, 66666667, 69776786, 69977687, 69997764, 88694864, 88796676, 88868878, 98476788, 98877687
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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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946968768486478^2 = 896749848488796768874868844484.
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MATHEMATICA
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With[{c={4, 6, 7, 8, 9}}, Table[Select[FromDigits/@Tuples[c, n], SubsetQ[c, IntegerDigits[ #^2]]&], {n, 8}]]//Flatten (* Harvey P. Dale, Sep 18 2016 *)
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CROSSREFS
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KEYWORD
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base,nonn
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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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