OFFSET
2,3
EXAMPLE
There are 4 divisors of 27. These are 1,3,9,27. The proper divisors of 27 are therefore 1,3,9. The largest of these that is coprime to d(27) = 4 is 9. So a(27) = 9. (Note that in this case, the largest divisor of 27 coprime to 4 is 27, not 9.)
MATHEMATICA
Table[Max[Select[Drop[Divisors[n], -1], GCD[DivisorSigma[0, n], # ] == 1 &]], {n, 2, 100}] (* Stefan Steinerberger, Dec 06 2008 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Dec 04 2008
EXTENSIONS
Extended by Ray Chandler and Stefan Steinerberger, Dec 05 2008
STATUS
approved