a^2 - b^2 ≡ (a+b)(a-b)

a and b are positive whole numbers with a>b

a^2 - b^2 is a prime number

why are a and b consecutive numbers

I don't understand your question.

Wait, but I know 7^2-6^2=13, which is prime...

Oh, but I know that difference between the consecutive numbers=sum of the numbers.