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all square mod n are squares: 1, 2, 3, 4, 5, 8, 10, 14
all square mod n are prime powers or 0 or 1: 1, 2, 3, 4, 5, 6, 7, 8, 9, E, 10, 12, 14, 18, 28
all prime not dividing n mod n are either primes not dividing n or 1: 1, 2, 3, 4, 6, 8, 10, 16, 20, 26
all square of prime not dividing n mod n are 1: 1, 2, 3, 4, 6, 8, 10, 20 (exactly the divisors of 20)

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