id:A094741 - OEIS Search Results

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Number of primes of the form k+1 where k is coprime to n, k < n.

+0
1

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; listen)

	OFFSET	`1,3`
	COMMENT	`If n is a prime, a(n) = pi(n). If n is even, a(n) = 1.`
	MATHEMATICA	`A094741[ n_ ] := Length[ Select[ Select[ Range[ n - 1 ], GCD[ #, n ] == 1 & ] + 1, PrimeQ ] ]; Table[ A094741[ i ], {i, 1, 100} ]`
	CROSSREFS	`Sequence in context: A055396 A057499 A064839 this_sequence A029234 A102613 A097019` `Adjacent sequences: A094738 A094739 A094740 this_sequence A094742 A094743 A094744`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 24 2004`
	EXTENSIONS	`More terms and Mathematica program from Keith Schneider, Jul 03 2007`

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Last modified November 29 12:46 EST 2009. Contains 167659 sequences.

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