# Tricky sequence

Author: mathforces
Problem has been solved: 28 times

Русский язык | English Language

Let $a_1, a_2, \dots, a_n$ be an arithmetic progression of integers such that $a_i$ is divisible by $i$ for all $i = 1, 2, \dots, n-1$ and $a_n$ is not divisible by $n$. Find the number of possible values of $n < 100$.