For which natural n is the expression 2^n + 8n + 5 an exact square?

Question

Mathematics

It seems like I know the solution to this problem. But I doubt very much that I decided correctly, so I decided to ask.
Problem (written in the title):
For which natural n is the expression 2^n + 8n + 5 an exact square?
You can solve it even with knowledge of 8-9 grades of school mathematics.
I will be very grateful.

Answer 1

https://ru.stackoverflow.com/questions/939658/%D0%...