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A071137
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Number of times 2n+p is prime, with p=1 or prime p < n.
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1
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1, 1, 1, 1, 2, 2, 2, 3, 2, 1, 2, 2, 3, 3, 4, 2, 3, 5, 2, 5, 5, 2, 3, 5, 4, 3, 5, 5, 3, 7, 3, 3, 7, 4, 5, 6, 3, 5, 7, 4, 4, 6, 5, 4, 8, 3, 6, 9, 5, 6, 7, 4, 5, 8, 6, 3, 6, 4, 3, 11, 5, 4, 10, 5, 6, 9, 7, 7, 10, 6, 3, 10, 6, 5, 12, 7, 6, 11, 5, 9, 12, 5, 7, 12, 8, 6, 10, 6, 7, 14, 7, 6, 11, 8, 9, 12, 7, 9
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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EXAMPLE
| a(11)=2 because 22+1 and 22+7 are primes.
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MATHEMATICA
| For[lst={}; n=1, n<=100, n++, If[PrimeQ[2n+1], cnt=1, cnt=0]; k=1; While[Prime[k]<n, If[PrimeQ[2n+Prime[k]], cnt++ ]; k++ ]; AppendTo[lst, cnt]]; lst
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CROSSREFS
| Cf. A071127.
Sequence in context: A014843 A116987 A159800 * A193990 A089367 A130192
Adjacent sequences: A071134 A071135 A071136 * A071138 A071139 A071140
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KEYWORD
| easy,nonn
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AUTHOR
| T. D. Noe (noe(AT)sspectra.com), May 28 2002
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