OFFSET
1,4
MATHEMATICA
Farey[n_] := Union[Flatten[Join[{0}, Table[a/b, {b, n}, {a, b}]]]]; f[n_] := Length@ Select[ Farey@ n, # <= 1/4 &]; Array[f, 56] (* Robert G. Wilson v, Nov 14 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved