--- In

primenumbers@yahoogroups.com,

"leavemsg1" <leavemsg1@...> wrote:

> choose N;

N = 187

> look at... N-1 and N+1; find out which one can be

> divided by 2 (only) and which one can be divided by 4.

N - 1 is divisible by 2 and not by 4

> if it's N-1, then both gcd(2^((N-1)/2) +0, +1, -1, ; N) = 1

> and... gcd(2^((N+1)/4) +0, +1, -1, ; N) = 1, iff N is prime.

Mod(2,N)^((N-1)/2) = Mod(151, 187)

Mod(2,N)^((N+1)/4) = Mod(128, 187)

187 is coprime to [150, 151, 152, 127, 128, 129].

187 is not prime.

David