Description

You can paint an asperand by pixels in three steps:

1. First you paint the inner square, with a side of k.
2. Then you need to paint one pixel, that's laying diagonally relative to the inner square that you just painted ( the bottom-right corner of the inner square is touching the top-left corner of the pixel ). Let's call it the "bridge".
3. Finally, you will need to paint the outer shape, connected diagonally to the "bridge" ( see the picture for more information ).

Here are some examples of this:

Your task is to find the number of pixels that need to be painted, for different k:

k = 1 => 11
k = 2 => 18
k = 3 => 26
k = 4 => 34

# Limitations are 1 ≤ k ≤ 1e9

The idea for this kata was taken from the Ukrainian Informatics Olympiad 2023.