

A094741


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


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
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OFFSET

1,3


COMMENTS

If n is a prime, a(n) = pi(n). If n is even, a(n) = 1.


LINKS

Table of n, a(n) for n=1..87.


MATHEMATICA

A094741[ n_ ] := Length[ Select[ Select[ Range[ n  1 ], GCD[ #, n ] == 1 & ] + 1, PrimeQ ] ]; Table[ A094741[ i ], {i, 1, 100} ] (* Keith Schneider, Jul 03 2007 *)


CROSSREFS

Sequence in context: A229944 A218533 A328578 * A285577 A324392 A340273
Adjacent sequences: A094738 A094739 A094740 * A094742 A094743 A094744


KEYWORD

nonn


AUTHOR

Amarnath Murthy, May 24 2004


EXTENSIONS

More terms from Keith Schneider, Jul 03 2007


STATUS

approved



