# Can't tell whether the following language is regular or not: [duplicate]

This question already has an answer here:

I have to decide if the following language is regular or not.

I suspect it is not regular, so I try using pumping lemma to prove it, but something goes wrong. Any help on how to use pumping lemma on this language would be appreciated:

$$\{{a^{n^2+2n}|n\ge 0}\}$$

I assume the language is regular.

I assume p is the pumping length.

I use the word ${a^{p^2+2p}}$ which is equal to ${a^{p^2}*a^{2p}}$

But after that i don't know how to end up in a contradiction to prove that it is not regular.