OFFSET
1,8
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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 of 1,2,1,2,1,1,1,1. 2 of these GCD's are > 1. So a(8)= 2.
MATHEMATICA
Table[Length[Select[Table[GCD[k, Floor[n/k]], {k, 1, n}], # > 1 &]], {n, 1, 80}] (* Stefan Steinerberger, Jul 23 2006 *)
PROG
(PARI) a(n) = sum(k=1, n, gcd(k, n\k) > 1); \\ Michel Marcus, Feb 16 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jul 12 2006
EXTENSIONS
More terms from Stefan Steinerberger, Jul 23 2006
STATUS
approved