OFFSET
1,2
COMMENTS
A120881(n) + a(n) = n.
EXAMPLE
For n = 8, we have the pairs {k,floor(n/k)} of {1,8},{2,4},{3,2},{4,2},{5,1},{6,1},{7,1},{8,1}. From these pairs we get the GCD's 1,2,1,2,1,1,1,1. 6 of these GCD's are = 1. So a(8) = 6.
MAPLE
a:=proc(n) local ct, k: ct:=0: for k from 1 to n do if gcd(k, floor(n/k))=1 then ct:=ct+1 else ct:=ct: fi: od: ct; end: seq(a(n), n=1..85); # Emeric Deutsch, Jul 24 2006
MATHEMATICA
Table[Length[Select[Table[GCD[k, Floor[n/k]], {k, 1, n}], # == 1 &]], {n, 1, 80}] (* Stefan Steinerberger, Jul 23 2006 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jul 12 2006
EXTENSIONS
STATUS
approved