(a^(n)b - ab^(n))/(2n)
When a and b are integers, and when the result is an integer too, i predict n is a prime number.
How can I prove it?
EDIT:
a and b mustn’t be equal to n and n mustn’t be 2.
"(a^(n)b - ab^(n))/(2n)
When a and b are integers, and when the result is an integer too, i predict n is a prime number."
Hmmm!
a = 4, b = 2, n = 4 gives (anb - abn)/(2n) = 56
a, b and (anb - abn)/(2n) are all integers, but n isn't prime.
Indeed
Then
a and b must not be equal to n.
You’ll need tighter constraints than that!
With a = 4, b = 2, n = 8, the result is 8128. n still not prime.
+42 
