#include <stdio.h>
#include <stdlib.h>

float sequence(float i)
{
    return (float)(1 / (3 * (i + 1)));
}

int main()
{
    float e;

    do
    {
        puts("Enter e(0.001 <= e <= 0.2):");
        scanf("%f", &e);
    }
    while(e < 0.001f || e > 0.2f);

    int i = 1;
    float n;

    do
    {
        n = sequence(i - 1) - sequence(i);
        if(n < e) break;

        printf("n(%d)-n(%d) = %.4g \n", i - 1, i, n);
        i++;
    }
    while(n >= e);

    return 0;
}