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A094741
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Number of primes of the form k+1 where k is coprime to n, k < n.
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1
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0, 1, 2, 1, 3, 1, 4, 1, 3, 1, 5, 1, 6, 1, 3, 1, 7, 1, 8, 1, 5, 1, 9, 1, 8, 1, 6, 1, 10, 1, 11, 1, 6, 1, 8, 1, 12, 1, 7, 1, 13, 1, 14, 1, 6, 1, 15, 1, 13, 1, 9, 1, 16, 1, 12, 1, 10, 1, 17, 1, 18, 1, 10, 1, 13, 1, 19, 1, 10, 1, 20, 1, 21, 1, 9, 1, 16, 1, 22, 1, 12, 1, 23, 1, 18, 1, 12
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| If n is a prime, a(n) = pi(n). If n is even, a(n) = 1.
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MATHEMATICA
| A094741[ n_ ] := Length[ Select[ Select[ Range[ n - 1 ], GCD[ #, n ] == 1 & ] + 1, PrimeQ ] ]; Table[ A094741[ i ], {i, 1, 100} ]
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CROSSREFS
| Sequence in context: A055396 A057499 A064839 * A029234 A102613 A097019
Adjacent sequences: A094738 A094739 A094740 * A094742 A094743 A094744
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 24 2004
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EXTENSIONS
| More terms and Mathematica program from Keith Schneider, Jul 03 2007
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