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**help please** on
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For every prime p consider all polynomials f(x) with integer coefficients from 1 to p and degree at most p−1, such that for all integers x the number f(2x)−f(x) is divisible by p.

Find the sum of all primes p<1000 such that the number of such polynomials is strictly greater than p⋅2^(p−2)