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Re:  math reference
Posted:
Aug 10, 2011 6:29 PM


I wrote:
> How about justifying a slight variant of the above statement: > > Statement: Every integer N that is 2 (mod 4) cannot be > expressed as the difference of two squares.
Of course the statement can be verified in a more easy way  I don't know what I was thinking/I doubt I was thinking at all:
Squares are 0 or 1 (mod 4) while [0 or 1 (mod 4)]  [0 or 1 (mod 4)] = 00=11=0 or 10=1 or 01=1=3 (mod 4) =/= 2 (mod 4).
Ulrich



