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A137291
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Numbers n such that prime(n)^2-2 is prime.
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6
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1, 2, 3, 4, 6, 8, 10, 12, 14, 15, 18, 20, 24, 27, 28, 31, 32, 34, 40, 43, 47, 48, 51, 52, 55, 62, 65, 68, 72, 82, 86, 87, 91, 94, 99, 100, 104, 107, 111, 119, 123, 128, 129, 130, 132, 133, 134, 135, 139, 141, 150, 152, 170, 172, 177, 180, 182, 191, 200, 202, 209, 211
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OFFSET
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1,2
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COMMENTS
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For n>=1, for these and only these numbers n, A242719(n) = prime(n)^2 + 1. Since A242719(n) >= prime(n)^2 + 1, then the equality is obtained on this and only this sequence.- Vladimir Shevelev, Sep 04 2014
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LINKS
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FORMULA
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EXAMPLE
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prime(24)*prime(24)-2 = 89*89-2 = 7919 is prime, so n=24 belongs to the sequence.
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PROG
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(Haskell)
a137291 n = a137291_list !! (n-1)
a137291_list = filter ((== 1) . a010051' . a049001) [1..]
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CROSSREFS
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KEYWORD
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easy,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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