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A128889
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a(n) = (2^(n^2) - 1)/(2^n - 1).
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5
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1, 5, 73, 4369, 1082401, 1090785345, 4432676798593, 72340172838076673, 4731607904558235517441, 1239150146850664126585242625, 1298708349570020393652962442872833, 5445847423328601499764522166702896582657, 91355004067076339167413824240109498970069278721
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OFFSET
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1,2
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COMMENTS
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The conjecture fails at n = 26, where 3340762283952395329506327023033 > 215656329382891550920192462661. Next counterexample for n = 30, but no odd counterexamples found so far. - Charles R Greathouse IV, Feb 17 2014
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LINKS
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FORMULA
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MAPLE
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a:=n->(2^(n^2)-1)/(2^n-1): seq(a(n), n=1..13);
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MATHEMATICA
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f[n_] := (2^(n^2) - 1)/(2^n - 1); Array[f, 12]
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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