C program to generate Geometric Progression(GP) series and find its sum

Write a C program to generate GP series and find its sum.

General form of GP series is a, ar, ar^2, ar^3, ar^4, ar^5 ...
a - First element of the sequence.
r - common ratio.

a = 2 and r = 5 GP series corresponds to these values are below.

2, 10, 50, 250 ....

Sum = a(1 - r^n)/(1 - r).  Where n is the number of elements in the series.
Sum = 2(1 - 5^4)/ (1 - 5) = 312 <=> 2 + 10 + 50 + 250

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

  int main() {
        int *data, value, ratio, sum, tmp, i, j, n;

        /* get the elements in series from user */
        printf("Enter the number of elements:");
        scanf("%d", &n);

        /* get first element of GP series from user */
        printf("1st Element in Geomentric Sequence:");
        scanf("%d", &value);

        /* get the ratio value from user */
        printf("Enter the value for ratio:");
        scanf("%d", &ratio);

        tmp = value;

        /* allocate memory to store values in GP series */
        data = (int *)malloc(sizeof(int) * n);

        /* stores the values of GP series in data array */
        for (i = 0; i < n; i++) {
                data[i] = tmp;
                printf("%d ", data[i]);
                tmp = value * pow(ratio, i + 1);
        }

        /* find the sum of the elements in GP series */
        sum = (value * (1 - pow(ratio, n)))/ (1 - ratio);

        /* print the results */

        printf("\nSum of the elements in GP series is %d\n", sum);

        return 0;

  }

Note:
gcc gpSeries.c -lm => link math library since we have used math function pow().

  Output:

  jp@jp-VirtualBox:~/$ gcc gpSeries.c -lm
  jp@jp-VirtualBox:~/$ ./a.out
  Enter the number of elements:4
  1st Element in Geomentric Sequence:2
  Enter the value for ratio:5
  2 10 50 250 
  Sum of the elements in GP series is 312