OFFSET
1,1
COMMENTS
No odd integer has any non-isolated divisors.
a(n) = 2n - A133945(2n).
MATHEMATICA
Table[Plus @@ EulerPhi[Select[Divisors[2n], If[ # > 1, IntegerQ[2n/(# - 1)]] || IntegerQ[2n/(# + 1)] &]], {n, 1, 80}] (* Stefan Steinerberger, Oct 04 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Oct 03 2007
EXTENSIONS
More terms from Stefan Steinerberger, Oct 04 2007
Extended by Ray Chandler, May 28 2008
STATUS
approved