OFFSET
1,2
EXAMPLE
a(6) = 4. The number of positive integers <= 7 that are coprime to 4 is four, these integers being 1, 3, 5 and 7. So a(7) = 4.
MATHEMATICA
a = {1}; For[n = 2, n < 80, n++, in = 1; co = 0; While[in < n + 1, If[GCD[a[[ -1]], in] == 1, co++ ]; in++ ]; AppendTo[a, co]]; a (* Stefan Steinerberger, May 29 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, May 04 2007
EXTENSIONS
More terms from Stefan Steinerberger, May 29 2007
STATUS
approved