If I have an equation such as 2n2 ┴ n ┴ 1 then the results of the equation will always be positive. Yet, if I write the results for the equation

1 4 11 22

and then take the finite differences, I discover that the number that precedes 1 in the series is 0, and before that there are negatives, which is impossible when considering the function.

what does this mean?