Find next 2 terms - 3^4, 4^5, 5^6.....?

Question

The next 2 answers would obviously be 6^7 and 7^8, but, I want to be able to work that out with a formula.
I can not figure out which formula to use with this question. Is there anyway to easily determine if it is arithmetic or geometric?
I am able to do these, however this one has me stumped as it uses - to the power -.
Any help would be greatly appreciated

I don't really want the answer, I need the formula on how to work it out. thanks

Answer 1

What you have appears to be a_n = (n + 2)^(n+3), n = 1, 2, 3, ...

Answer 2

Try to use this site:
http://www.research.att.com/~njas/sequences/