MathCastle
Number TheorySuperchallengeFermat, Euler and Wilson

Fermat, Euler and Wilson · Superchallenge problem

For how many integers xx with 1≤x≤9101 \le x \le 910 is

1+x+x2+⋯+x20271 + x + x^2 + \cdots + x^{2027}

divisible by 9191?