Write both sides as 1 first. Then write this:

The latter number is equal to the sum of the first two numbers.

3= 1+2,5=3+2,8=5+3, 13=8+5

Then as long as there is a function f(x). Its f (1) = 1, f (2) = 2, f (3) = 3.

You can construct a function such as

Then it can use its f(4) and f(5) as columns 4 and 5.

This can also be done: one item is the sum of its first three items.