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A093312
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Least k such that (2n+2k)+1 and (2n*2k) +1 are both primes.
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1
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1, 9, 3, 1, 3, 3, 1, 3, 2, 1, 9, 2, 1, 6, 3, 4, 6, 8, 10, 3, 5, 1, 3, 2, 1, 3, 12, 1, 15, 5, 13, 9, 3, 1, 18, 3, 4, 3, 2, 4, 33, 2, 1, 12, 3, 7, 6, 3, 1, 3, 2, 16, 15, 2, 13, 9, 17, 25, 15, 5, 4, 6, 26, 1, 9, 8, 1, 30, 5, 16, 3, 2, 1, 15, 6, 7, 12, 3, 7, 15, 5, 7, 3, 2, 4, 3, 12, 1, 6, 5, 7, 36, 3, 22
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| a(4) = 1, 8+2*2 +1 =11 and 8*2*2 +1 = 17 are both prime.
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MATHEMATICA
| f[n_] := Block[{k = 1}, While[ !PrimeQ[2n + 2k + 1] || ! PrimeQ[2n*2k + 1], k++ ]; k]; Table[ f[n], {n, 95}] (from Robert G. Wilson v Apr 24 2004)
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CROSSREFS
| A093481/2.
Sequence in context: A010159 A097528 A065416 * A154629 A154489 A085579
Adjacent sequences: A093309 A093310 A093311 * A093313 A093314 A093315
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 14 2004
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EXTENSIONS
| Edited, corrected and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 24 2004
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