How many integers are there such that divides for every positive integer ?
Solution
To solve the problem, we are tasked with finding the number of integers such that divides for every positive integer .
First, observe that if for every integer , then for each in particular values, such as . This means that divides the polynomial evaluated at these integers.
An important observation is that the polynomial corresponds to the characteristic property of a finite field. Specifically, for a prime implies that or the multiplicative order of divides 13.
The roots of the polynomial are precisely the elements of the finite field if is a prime power.
The polynomial can be factored using:
Notice that the polynomial implies that should divide each of the factors, either directly or by induction that all prime divisors of must also be Fermat primes where necessary.
At this point, it is particularly significant that the prime divisors must satisfy . Therefore, we need to find all integer divisors greater than 1 of order 13. This includes small prime powers such that for each prime , , which in the case of modulo 13 implies possibly restricted to to the factor set characteristics.
Ultimately, using the properties of congruences and finite fields, we find that:
For such that divides for all integers , we have the specific minimal divisors governing congruence properties from derived direct or field characteristics:
Hence, the number of such integers is: