5. shapeArea


Task

Below we will define an n-interesting polygon. Your task is to find the area of a polygon for a given n.

A 1-interesting polygon is just a square with a side of length 1. An n-interesting polygon is obtained by taking the n - 1-interesting polygon and appending 1-interesting polygons to its rim, side by side. You can see the 1-, 2-, 3- and 4-interesting polygons in the picture below.

area

Example

  • For n = 2, the output should be
    shapeArea(n) = 5;

  • For n = 3, the output should be
    shapeArea(n) = 13.

Input/Output

  • [execution time limit]
    4 seconds (py3)

  • [input] integer n
    Guaranteed constraints: 1 ≤ n < 104.

  • [output] integer
    The area of the n-interesting polygon.

My Solution

def shapeArea(n):
    area = 1 + 2 * (n - 1) * n
    return area