×

# Number Theory: Divisibility.

Show that there are infinite positive integers $$n$$ such that $$n+1$$ divides $$5^n - 1$$.

Note by Lucas Nascimento
7 months, 1 week ago

Sort by:

By Fermat's little Theorem, all numbers n other the 4 which are 1 less than a prime number satisfies the condition. · 7 months ago

With the exception of 4? No? · 7 months ago

Yes thanks I forgot to mention that. · 7 months ago

Correct. · 7 months ago