A102614 Denominators of the reduced fractions of the ratios of the number of primes less than n over the number of composites less than n.

1, 1, 1, 1, 2, 1, 3, 1, 5, 3, 6, 7, 7, 4, 3, 5, 10, 11, 11, 3, 13, 7, 14, 5, 16, 17, 2, 19, 19, 2, 20, 21, 2, 23, 24, 25, 25, 13, 9, 7, 28, 29, 29, 15, 31, 16, 32, 11, 34, 7, 12, 37, 37, 19, 39, 5, 41, 21, 42, 43, 43, 22, 5, 23, 47, 8, 48, 49, 50, 51, 51, 13, 52, 53, 18, 55, 8, 19, 57, 29

Offset

1,5

Links

Table of n, a(n) for n=1..80.

Formula

pi(n) is the number of primes <= n. Number of composites <= n = n - pi(n).

Mathematica

frac[n_]:=Module[{ps=PrimePi[n]}, ps/(n-ps)]; Denominator/@Array[frac, 90] (* Harvey P. Dale, May 19 2011 *)

Prog

(PARI) pixovcmpx(n) = for(x=1, n, print1(denominator(pi(x)/(x-pi(x)))", ")) pi(n) = \Number of primes less than or equal to n. { local(c, x); c=0; forprime(x=1, n, c++); return(c) }

Crossrefs

Sequence in context: A283463 A283464 A323184 * A307149 A276421 A330547

Adjacent sequences: A102611 A102612 A102613 * A102615 A102616 A102617

Keyword

frac,nonn

Author

Cino Hilliard, Jan 30 2005

Status

approved