#include <math.h>
#include <stdio.h>
#include <stdlib.h>
int main()
{
   int x,i,n;
    double fact;
    double sum=0,k=1;
    x=-2;
            i=0; sum=0; k=1;
                while (fabs(k)>=1.0E-9) {
                    int j;
                    fact=1;
                    for (j=1;j<=i;++j)
                        fact*=j;
                    k=pow(x,i)/fact;
                    sum+=k;
                    ++i;
                    printf("%d,%f\n",i,k);
                }
    printf("%lf\n",sum);
    return 0;
}

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