A049811 - OEIS

%I #8 Nov 14 2012 10:12:00

%S 1,1,1,1,1,1,2,3,4,5,6,7,8,9,11,12,14,15,17,18,20,22,25,26,29,31,33,

%T 35,39,40,44,46,49,51,55,57,62,65,69,71,76,78,84,87,90,93,99,101,107,

%U 110,115,119,126,129,135,138,144,148,156,158

%N a(n)=number of Farey fractions of order n that are <=1/7; cf. A049805.

%t Farey[n_] := Union[Flatten[Join[{0}, Table[a/b, {b, n}, {a, b}]]]]; f[n_] := Length@ Select[ Farey@ n, # <= 1/7 &]; Array[f, 60] (* _Robert G. Wilson v_, Nov 14 2012 *)

%Y Cf. A005728, A049806, A049807, A049808, A049809, A049810, A049812, A049813, A049814.

%K nonn

%O 1,7

%A _Clark Kimberling_