Re: Elliptic curves over finite fields

["Prof. J. E. Cremona" <John.Cremona@nottingham.ac.uk>]

If ap = ellap(E,p) is the Trace of Frobenius at p then

apr = trace(Mod(x,x^2-ap*x+p)^r)  is the trace of Frobenius^r

and so the number you want is 1+p^r-apr.

John Cremona
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