Centered Polygonal Number

In mathematics, the centered polygonal numbers are a class of figurate numbers, each formed by a central dot surrounded by polygonal layers of dots with a constant number of sides. Each side of a polygonal layer contains one more dot than the corresponding side of the previous layer, so from the second layer onward, each layer of a centered k-gonal number adds k more dots than the layer before it. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/