English Tech/Engineering Mathematics & Statistics calculator

"We can simplify this expression even further by using Euler's formula for complex numbers, namely, e2inπ = cos(2nπ) + i•sin(2nπ) = 1 + i•0 = 1, since cos(2nπ) = 1, and sin(2nπ) = 0, ***for n integer***."

...does it mean 1) "for a number "n" of integers" [for a given number of integers], 2) "for n which must be an integer", 3) for the number n, which is an integer", 4) or what?

thanks!