A049813 a(n)=number of Farey fractions of order n that are <=1/9; cf. A049805.

1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 16, 17, 19, 20, 22, 23, 25, 27, 30, 31, 34, 36, 38, 40, 43, 44, 48, 50, 53, 55, 59, 60, 64, 66, 69, 72, 77, 79, 84, 86, 90, 93, 98, 100, 105, 108, 112, 115, 121, 122

Offset

1,9

Links

Table of n, a(n) for n=1..60.

Mathematica

Farey[n_] := Union[Flatten[Join[{0}, Table[a/b, {b, n}, {a, b}]]]]; f[n_] := Length@ Select[ Farey@ n, # <= 1/9 &]; Array[f, 60] (* Robert G. Wilson v, Nov 14 2012 *)

Crossrefs

Cf. A005728, A049806, A049807, A049808, A049809, A049810, A049811, A049812, A049814.

Sequence in context: A354928 A195044 A033112 * A354925 A362184 A368904

Adjacent sequences: A049810 A049811 A049812 * A049814 A049815 A049816

Keyword

nonn

Author

Clark Kimberling

Status

approved