Consecutive Prime Sum

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Some prime numbers can be expressed as sums of other consecutive prime numbers.

For example

5 = 2 + 3
17 = 2 + 3 + 5 + 7
41 = 2 + 3 + 5 + 7 + 11 + 13

Your task is to find out how many prime numbers which satisfy this property are present in the range 3 to N subject to the constraint that summation should always start with number 2.

Write code to find out a number of prime numbers that satisfy the above-mentioned property in a given range.

Input Format:

Each test case contains a number N <= 1000000000

Output Format:

Print the total number of all such prime numbers which are less than or equal to N.

 

Code:

import math

def isprime(n):

    if (n==2 or n==3):

        return 1

    if (n==1 or n%2==0 or n%3==0 ):

        return 0

    for i in range(5,int(math.sqrt(n)+1),6):

        if(n%i==0 or n%(i+2)==0 ):

            return 0

    return 1

n=int(input())

sum=2

i=3

c=0

while(sum<=n):

    if(isprime(i)==1):

        sum+=i

        if(sum<=n and isprime(sum)==1):

            c+=1

    i=i+2

print(c)

Screenshots:






 

 


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