16 questions linked to/from Fermat numbers are coprime
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$(a^{2^n}+1,a^{2^m}+1)=1 or 2$ [duplicate]

Prove that if $m\not =n,a$ are positive integers then $(a^{2^n}+1,a^{2^m}+1)$ is $1$ if $a$ is even and $2$ if $a$ is odd. I solve the problem in the following way: I assume that $m>n$ then a^{...
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Prove that if $a,m,n \in \mathbb{Z}^+$ and $m \ne n$ then $\gcd(a^{2^m}+1,a^{2^n}+1)$ is 1 if a is even and 2 if a is odd. [duplicate]

I know that if a pime q|a^2^m+1 and q divides a^2^n+1 then q divides their sum and difference but i don't know how to proceed further. please help
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Problems regarding GCD [duplicate]

If $m > n$ and $a,m,n$ are positive, with $m$ not equal to $n$, find the greatest common divisor of $2^{2^m}+1, 2^{2^n}+1$. Please solve this problem using Euclid's algorithm. I tried to use ...
Find $(a^{2^m}+1, a^{2^n}+1)$ when a is odd and a,m,n are positive integers and m is not equal to n. I know that the hcf is a multiple of two but I can't prove that it is 2 which is the answer. Plz ...
Fermat numbers are shown by: $F_m = 2^{2^m} + 1$. How can I prove that for any $m ≠ n$, I can have $(F_m, F_n) = 1$, or coprime?