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Search: id:A118580
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| A118580 |
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Least k such that 10^n + k is a Sophie Germain prime and the lesser of a twin prime pair. |
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+0
1
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| 2, 1, 79, 19, 91, 361, 211, 1699, 1651, 2359, 3001, 26569, 61, 19759, 18109, 29911, 13741, 4381, 3811, 13429, 15469, 27331, 11431, 49111, 47929, 17041, 227971, 48979, 315511, 65299, 86359, 78049, 2449, 69949, 136579, 24781, 149779, 256171, 143551
(list; graph; listen)
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OFFSET
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0,1
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FORMULA
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a(n) = A118479(n+1) - 10^n.
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EXAMPLE
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10^1+1=11, 11 is a Sophie Germain prime and 11 and 13 are twin prime pairs.
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MATHEMATICA
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f[n_] := Block[{k = 10^(n - 1)}, While[ !PrimeQ[k] || !PrimeQ[k + 2] || !PrimeQ[2k + 1], k++ ]; k - 10^(n - 1)]; Array[f, 40] (from Robert G. Wilson v (rgwv(at)rgwv.com), May 13 2006)
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CROSSREFS
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Cf. A118479.
Sequence in context: A104024 A096681 A067276 this_sequence A118558 A095837 A095835
Adjacent sequences: A118577 A118578 A118579 this_sequence A118581 A118582 A118583
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KEYWORD
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nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), May 07 2006
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