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A337261
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Numbers k such that the digits of 4^k cannot be rearranged to form the digits of t^2, for t not a power of 2.
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1
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OFFSET
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1,3
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COMMENTS
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Leading zeros are not allowed.
2^odd cannot be rearranged to a square number: odd powers of 2 are congruent to 2,5,8 mod 9; squares are congruent to 0,1,4,7 mod 9; and rearranging preserves the mod-9 value.
If it exists, a(9) > 78.
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REFERENCES
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Don Reble, Posting to Sequence Fans Mailing List, Aug 21 2020
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LINKS
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EXAMPLE
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4 is not here because 4^4 = 256 -> 625 = 25^2.
10 is not here, because 4^10 = 1048576 -> 1056784 = 1028^2.
11 is here, even though 4^11 = 4194304 -> 0413449 = 643^2, because leading zeros aren't allowed.
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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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