def sum_gp(a,n,r):
 import math
 
 total = (a * (1 - math.pow(r, n ))) / (1- r)
 return total
def is_not_prime(n):
    import math
    
    result = False
    for i in range(2,int(math.sqrt(n)) + 1):
        if n % i == 0:
            result = True
    return result