budd@ihlpf.UUCP (10/27/83)
#R:arizona:-558700:ihlpf:6200019: 0:371
ihlpf!dap1 Oct 24 19:46:00 1983
The second result is easy. It's the same as saying that
n^2 - 1 = (n - 1)(n + 1) | 24 = 3*4*2 ('|' means divisibility).
Since n is prime and greater than 5, we know that:
a. one of n-1 or n+1 is divisible by three.
b. one of n-1 or n+1 is divisible by two
c. one of n-1 or n+1 is divisible by four.
So the whole thing is divisible by 24.
Darrell Plank
Bell Labs