How to solve a problem in excel?

Question

excel

The algorithm for calculating the functions F(n) and G(n) is given by the following relations:
F(1) = G(1) = 1
F(n) = 2 F(n–1) + G(n–1) – 2n, if n > 1
G(n) = F(n–1) +2 G(n–1) + n if n > 1
What is the value of F(14) + G(14)?

Answer 1

in the first column there will be n, in the second F, in the third G
in the first line F(1) = G(1) = 1
in the second line write the formula for F and the formula for G,
stretch the formulas down.
Everything.
If there are specific difficulties, then show how you are trying to do and what does not work.