problem2.c

#include <stdio.h>
#include <math.h>

int main(void)
{
    int max;
    int res = 0;
    // input last term
    // printf("Enter the maximum: ");
    scanf("%d", &max);
    int i = 1;
    char c = 253; // 253 is the ascii code for the square symbol
    while (1)
    {
        if (i > max)
        {
            printf(" = %d", res);
            break;
        }
        else
        {
            if (i == max)
            {
                printf("%d%c", i, c);
            }
            else
            {
                printf("%d%c+", i, c);
            }

            res = res + pow(i, 2);
            i++;
        }
    }
}

problem3.c

#include <stdio.h>
#include <math.h>

int main(void)
{
    int max;
    int res = 0;
    // input last term
    // printf("Enter the maximum: ");
    scanf("%d", &max);
    int i = 1;
    while (1)
    {
        if (i > max)
        {
            printf(" = %d", res);
            break;
        }
        else
        {
            if (i == max)
            {
                printf("%dx%d", i, i + 1);
            }
            else
            {
                printf("%dx%d + ", i, i + 1);
            }

            res = res + i * (i + 1);
            i++;
        }
    }
}

problem_1.c

#include <stdio.h>

int main(void)
{
    // sum of the series
    int sum = 0;
    // input last term
    // printf("Enter the maximum: ");
    int max;
    scanf("%d", &max);
    // loop
    int i = 5;
    while (1)
    {
        if (i > max)
        {
            break; // the last term cannot exceed the maximum
        }
        
        printf("%d", i);
        i += i;
        if (i > max)
        {
            break;
        }
        else
        {
            printf(",");
        }
    }

    return 0;
}

1. Write a C program that will print all the numbers of the following series up to n (i.e. the last term cannot exceed n).
   SAMPLE INPUT
   30
   100
   SAMPLE OUTPUT
   5,10,20
   5,10,20,40,80

2. Write a C program that will calculate the sum of the mentioned series up to its n terms.
   SAMPLE INPUT
   5
   8
   SAMPLE OUTPUT
   12+22+32+4²+52 = 55
   1²+2²+3²+4²+5²+6²+7²+8² = 204

3. Write a C program that will calculate the sum of the mentioned series up to its n terms.
   SAMPLE INPUT
   5
   8
   SAMPLE OUTPUT
   1x2 + 2x3 + 3x4 + 4x5 + 5x6 = 70
   1x2 + 2x3 + 3x4 + 4x5 +5x6+6x7+7x8+ 8x9= 240