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Search: id:A090190
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| A090190 |
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Symmetric primes: an odd prime p is symmetric if there exists an odd prime q such that |p-q|=gcd(p-1,q-1). |
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+0
2
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| 3, 5, 7, 11, 13, 17, 19, 29, 31, 37, 41, 43, 53, 59, 61, 67, 71, 73, 79, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 269, 271, 277, 281, 283, 293, 307, 311
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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P. Fletcher, W. Lindgren and C. Pomerance, Symmetric and asymmetric primes, J. Number Theory 58 (1996) 89-99.
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EXAMPLE
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Any twin prime is symmetric since 2=gcd(p-1,p+1) for any odd prime p.
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MATHEMATICA
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f[n_] := Block[{k = 2}, While[k < 10^3 && Abs[n - Prime[k]] != GCD[n - 1, Prime[k] - 1], k++ ]; If[k == 10^3, 0, Prime[k]]]; Select[ Prime[ Range[2, 100]], f[ # ] != 0 &] (from Robert G. Wilson v Sep 19 2004)
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CROSSREFS
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Complement gives A090191.
Sequence in context: A065389 A123567 A059645 this_sequence A065041 A065393 A132143
Adjacent sequences: A090187 A090188 A090189 this_sequence A090191 A090192 A090193
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KEYWORD
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nonn
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AUTHOR
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S. R. Finch (Steven.Finch(AT)inria.fr), Jan 21 2004
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 19 2004
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