Mathematical notation of set with $n+3$ members One of the math problems I have describes a set of numbers this way:

let there be a set A such that $A=\{{1,2,3,...,n+3}\}$.

I don't understand what the $n+3$ means and how the set actually looks like.

The $n$ is arbitrary and finite. Basically, choose an $n$ so
$$ A_n = \{ 1, 2, \ldots, n, n+1, n+2, n+3 \}.$$
For example, $A_4 = \{1, 2, \ldots, 5, 6, 7 \}.$
