A085962 Numerators of Farey fractions with prime numerators and denominators.

2, 2, 3, 2, 2, 2, 3, 3, 2, 5, 2, 3, 2, 2, 3, 5, 3, 7, 2, 5, 2, 2, 3, 3, 2, 5, 2, 3, 5, 7, 3, 7, 2, 5, 11, 2, 2, 3, 2, 3, 3, 2, 5, 5, 2, 7, 3, 5, 7, 3, 7, 11, 2, 5, 13, 11, 2, 2, 2, 3, 3, 2, 3, 5, 3, 2, 5, 7, 5, 2, 7, 3, 5, 7, 11, 3, 7, 11, 2, 13, 5, 13, 11, 17, 2, 2, 2, 3, 2, 3, 3, 2, 5, 3, 5, 3, 2, 5, 7, 7, 5

Offset: 3

Author

Cino Hilliard, Aug 17 2003

Keywords

• easy
• nonn
• frac

Crossrefs

Cf. A085693.

Programs

PARI

\ Farey sequence of order n fareyct(n) = { forprime(x=2,n, y = farey(x); \ print1(y","); ) } farey(n) = { c=0; m=n*(n-2)+2; a=vector(m); forprime(x=1,n, forprime(y=x,n, v = x/y; if(v<1, c++; a[c]=v; ) ) ); a = vecsort(a); c=0; for(x=2,m, if(a[x]<>a[x-1] & a[x]<>0, print1(numerator(a[x])","); c++; ) ); return(c) }