I did not post this comment, I am very good with quadratic sequences and can do this easily. This may have been one of my friends playing around but I have certainly never posted the comment about not understanding it.
How to find the nth term of a quadratic sequence of numbers. (A quadratic sequence of numbers includes a n^2 term) ...apologies for the distorted voice, I didn't ...
Nth term quadratic sequences
Finding the nth term of a quadratic sequence.
Quadratic sequences from the start
This video goes through a method of finding the nth term of a quadratic sequence, with relevant example and questions to try out. A few assumptions are made, ...