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A136952
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Numbers k such that k and k^2 use only the digits 0, 4, 5, 7 and 9.
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1
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0, 7, 70, 97, 700, 970, 997, 7000, 9700, 9747, 9970, 9997, 70000, 70997, 75997, 97000, 97470, 99700, 99970, 99997, 700000, 709970, 709997, 759970, 759997, 970000, 974700, 997000, 999700, 999970, 999997, 7000000, 7050497, 7099700, 7099970, 7099997, 7450497, 7599700, 7599970, 7599997, 9700000, 9747000, 9970000, 9979757, 9997000
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OFFSET
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1,2
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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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707075495050497^2 = 499955755700905407544579947009.
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MATHEMATICA
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With[{c={0, 4, 5, 7, 9}}, Select[FromDigits/@Tuples[c, 7], SubsetQ[ c, IntegerDigits[ #^2]]&]] (* Harvey P. Dale, Nov 19 2019 *)
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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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