Talk:Root of unity
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Note that, contrary to first appearances, not all coefficients of all cyclotomic polynomials are 1, −1, or 0; the first polynomial where this occurs is Φ105, since 105=3 is the first product of three odd primes.
- It's not immediately clear to me why this property of 105 implies it's the first cyclotomic polynomial with coefficient not equal to 1, -1, or 0. Is this really easy to see, or something I've just forgotten? If it's pretty easy to show, then a quick justification would be good, if it's not very easy to show, I don't think the fact should be mentioned, it leaves the reader dangling.