strange-advertising.py

#!/bin/python3

import math
import os
import random
import re
import sys

#
# Complete the 'viralAdvertising' function below.
#
# The function is expected to return an INTEGER.
# The function accepts INTEGER n as parameter.
#

def viralAdvertising(n):
    x = 2
    res = 2
    for _ in range(1, n):
        x = (x * 3) // 2
        res += x
    return res
        
if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    n = int(input().strip())

    result = viralAdvertising(n)

    fptr.write(str(result) + '\n')

    fptr.close()