When product sigma(k)/d(k) = integer
Leroy Quet
qq-quet at mindspring.com
Mon Jun 27 19:56:21 CEST 2005
I wrote in response to Jack Brennen's observation that the only values
which are not integer occur when n= 2 or 10, for n < 5000:
>Hmmmm....the question occurs to me and to most probably to others on the
>list, is the sequence of n's where the product to n is not an integer a
>finite sequence?
>And if so, what is the top n? Is it 10?
*Proving* the rest of the values of
product{k=1 to n} sigma(k)/d(k)
are integers seems like it might be a tricky problem.
I guess I should post that
product{k=1 to n} sigma(k)/d(k)
=
product{p=primes} product{k>=1}
((p^(k+1)-1)/((p-1)(k+1)))^(floor(n/p^k)-floor(n/p^(k+1)))
=
product{p=primes} product{k>=1} ((p^(k+1)-1)*k/((p^k
-1)(k+1)))^floor(n/p^k).
Maybe this will lead someone to a proof that values of the product for
all n above n=10 are integers.
Or maybe not.
thanks,
Leroy Quet
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