[seqfan] Re: Counting k! == +-1 (mod n), k>=0

[israel at math.ubc.ca]

Obviously k is at most the least prime factor of n.  
For the number of factorials = +1 mod n, see A049046.
I couldn't find the number =-1 mod n in OEIS. 

Robert Israel
University of British Columbia and D-Wave Systems

On Apr 1 2014, Richard J. Mathar wrote:

> i) Just by curiosity: is there anything known about the function w(n) 
> counting the number of k>=0 (or k>0 alternatively) such that k! = +-1 
> (mod n)? This is mentioned in A071710. The interest would be in general 
> n, prime or not.
>
>Can we say, at least, that these k with that modular property are finite
>for each n such that w(n) < infinity, although the candidates k are not
>bounded by the definition?