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A214717
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Least m>0 such that 4^n-m and n-m are relatively prime.
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2
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2, 1, 1, 3, 1, 3, 2, 1, 1, 3, 1, 1, 2, 1, 2, 3, 1, 1, 2, 1, 1, 3, 1, 1, 2, 5, 1, 3, 1, 1, 2, 1, 1, 3, 1, 3, 2, 1, 1, 3, 1, 1, 2, 1, 2, 3, 1, 1, 2, 1, 1, 3, 1, 1, 2, 3, 2, 3, 1, 1, 2, 1, 1, 3, 1, 3, 2, 1, 1, 3, 1, 1, 2, 1, 1, 3, 1, 3, 2, 1, 1, 3, 1, 1, 2, 3, 1
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OFFSET
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1,1
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LINKS
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EXAMPLE
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gcd(4^6-1,5) = 5, gcd(4^6-2,4) = 2, gcd(4^6-3,3) = 1, so a(6) = 3.
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MATHEMATICA
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Table[m = 1; While[GCD[4^n - m, n - m] != 1, m++]; m, {n, 1, 140}]
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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