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A076473
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Number of pairs (p,q) of successive primes with p+q<=n and gcd(p+q,n)=1.
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2
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0, 0, 0, 0, 0, 1, 1, 1, 2, 0, 2, 1, 3, 1, 1, 1, 3, 1, 4, 0, 2, 1, 4, 1, 4, 1, 2, 1, 5, 0, 6, 1, 2, 1, 4, 1, 7, 1, 2, 0, 7, 1, 8, 1, 1, 1, 8, 1, 7, 0, 2, 1, 9, 1, 7, 1, 3, 1, 9, 0, 10, 1, 3, 1, 6, 1, 10, 1, 4, 0, 11, 1, 11, 1, 3, 1, 10, 1, 12, 0, 4, 1, 12, 1, 9, 1, 4, 1, 13, 0, 10, 1, 4, 1, 10, 1, 14, 1, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,9
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COMMENTS
| a(n) = A076471(n) - A076472(n).
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EXAMPLE
| n=27: gcd(2+3,27)=1, gcd(3+5,27)=1, gcd(5+7,27)=3, gcd(7+11,27)=9, gcd(11+13,27)=3, hence a(27)=2.
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CROSSREFS
| Cf. A000010.
Sequence in context: A078152 A191247 A028932 * A163160 A029240 A025803
Adjacent sequences: A076470 A076471 A076472 * A076474 A076475 A076476
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 14 2002
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