Set-builder notation

$A=\{7,14,21,28\}$ is the set-builder notation $\{x \in \mathbb N:x=7n, n \in \mathbb N \text{ and } 1\le n \le 4\}$ right?

• A={7,14,21,28} (it's not a sequence). It looks correct to me. I would probably use $\land$ instead of comma or descriptive text ("and") though. Not sure if it is necessary with things like $\forall$ etc, guess it depends on the formality level. – Emil Feb 19 '16 at 9:41
• Wellcome to MSE !! – HK Lee Feb 19 '16 at 9:45
• It is indeed correct but it does carry some redundancies (you've said that $n \in \mathbb{N}$, which already means that $x=7n \in \mathbb{N}$, so saying prior to that that $x \in \mathbb{N}$ is unnecessary). – Irregular User Feb 19 '16 at 10:14