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A049812
a(n)=number of Farey fractions of order n that are <=1/8; cf. A049805.
8
1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 15, 16, 18, 19, 21, 22, 25, 27, 29, 31, 34, 35, 38, 40, 43, 45, 49, 50, 54, 56, 59, 61, 66, 68, 73, 76, 79, 82, 87, 89, 95, 97, 101, 104, 110, 112, 117, 120, 125, 129, 136, 138
OFFSET
1,8
MATHEMATICA
Farey[n_] := Union[Flatten[Join[{0}, Table[a/b, {b, n}, {a, b}]]]]; f[n_] := Length@ Select[ Farey@ n, # <= 1/8 &]; Array[f, 60] (* Robert G. Wilson v, Nov 14 2012 *)
KEYWORD
nonn
STATUS
approved