So i suppose you are asking what is known about the generalization of FLT in the form;
x^n+y^n=z^(n+d) with d not n*k x,y,z>0
At least x^3+y^3=z^2 has solutions;
1^3+2^3=3^2 is one.
11^3+37^3=228^2 is another.
Here is a lecture on some generalized versions of Fermat's equation.
http://math.hawaii.edu/numbertheory2...tt-Lecture.pdf
A good starting point is probably to always check the corresponding elliptic curves that were used to make the original Fermat problem connection eg by Frey and Hellegouarch
like here
https://en.wikipedia.org/wiki/Frey_curve
you may check out info found here
http://arxiv.org/pdf/math/9905208.pdf
and also here
https://en.wikipedia.org/wiki/Fermat...lan_conjecture
Regarding that last one as of 2015 only known;
As of 2015, the following ten solutions to (1) are known:[1]
1^m+2^3=3^2
2^5+7^2=3^4
13^2+7^3=2^9
2^7+17^3=71^2
3^5+11^4=122^2
33^8+1549034^2=15613^3
1414^3+2213459^2=65^7
9262^3+15312283^2=113^7
17^7+76271^3=21063928^2
43^8+96222^3=30042907^2
Last edited by masque de Z; 08-13-2015 at 11:32 PM.