All numbers are natural numbers. (Integer of n>0).
How to solve the equation? Prime 7 can not solve the answers.
The answers are
Mathcad never was the tool to solve diophantic equations (apart from an extension pack which worked only in a very early version of MC).
You get a result in MC15 but its in no way helpful:
Maybe Luc can show us what MC11 with Maple can come up with