> %C A280098 Conjecture: only the integers k in {1, 3, 4, 6, 8, 12, 24}
> have the property that [the sum of the divisors of (k*n-1)] / k is
> always an integer. - _Robert G. Wilson v_, Dec 25 2016
That looks easy to prove. Which means that someone already has,
long long ago. Does anyone have a reference?
--
Don Reble djr at nk.ca