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MersennePrime.c
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MersennePrime.c
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#include <stdio.h>
#include <math.h>
int main()
{
int limit;
printf("Enter your limit:");
scanf("%d",&limit);
SieveMersennePrime(limit);
}
int isPrime(int x)
{
if (x==1)
{
return 0;
}
else if (x==2)
{
return 1;
}
else
{
int lim = sqrt(x);
for (int i = 2; i <= lim; i++)
{
if (isPrime(i))
{
if (x%i==0)
{
return 0;
}
}
}
return 1;
}
}
int SieveMersennePrime(int y)
{
int arr[y+1];
for (int j = 2; j <=y ; j++)
{
arr[j] = j;
}
int sievelim = sqrt(y);
for (int k = 2; k <= sievelim; k++)
{
if (isPrime(k))
{
int mul = y/k;
for (int n = 2; n <= mul; n++)
{
arr[n*k] = -1;
}
}
}
for (int m = 2; m <= y; m++)
{
if (arr[m]!=-1)
{
if (isPowerOfTwo(arr[m]+1))
{
printf("%d ",arr[m]);
}
}
}
}
int isPowerOfTwo(int n)
{
if (n == 0)
return 0;
while (n != 1)
{
if (n%2 != 0)
return 0;
n = n/2;
}
return 1;
}