ÖMO 1990 Problem 1

Determine the number of integers $n$ with $1 \le n \le N=1990^{1990}$ such that $n^2-1$ and $N$ are coprime.

Dataset text AI-MO AoPS. Quoted with source.

Solutions

No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.