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A194639
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Indices of records in A194591 when it is restricted to odd indices.
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13
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1, 5, 13, 47, 59, 109, 241, 335, 1109, 1373, 1447, 14893, 52267, 56543, 649603, 838441, 8840101, 16935761, 100604513, 118373279, 270704167, 1355477231
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listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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Integers for which the smallest k in A194591 such that (2*n-1)*2^k - 1 or (2*n-1)*2^k + 1 is prime (A194638) increases.
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REFERENCES
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Wilfrid Keller, personal communication, 2010.
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LINKS
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MATHEMATICA
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l = -1; Flatten[Table[n = 2*n - 1; k = 0; While[! PrimeQ[n*2^k - 1] && ! PrimeQ[n*2^k + 1], k++]; If[k > l, l = k; n, {}], {n, 10^5}]] (* Arkadiusz Wesolowski, Sep 04 2011 *)
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CROSSREFS
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KEYWORD
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more,nonn
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AUTHOR
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EXTENSIONS
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a(22) was found in 2002 by Wilfrid Keller.
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STATUS
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approved
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