pattern

Question: Write a program that generates output shown in left image.

The code is:

#include<stdio.h>
// this program works well when the value of rows is less than 20
void main()
{

 int n = 5;
 int i = 0 , j = 0;

 printf("Enter no of rows: ");
 scanf("%d",&n);
 for(i = 0; i<n ;i++)
 {

  for(j = i; j >=0;j--)
  {

   printf("%3d ", fun(i,j));
  }
  printf("\n");
 }
}

int fun(int a , int b )
{
 int sum = 0 ;

 int i = 0 , j = 0;

 for(i = 0 ; i <= a ; i++)
 {

  for(j = 0 ; j <= i ; j++)
  {

   sum++;
   if( i==a && b==j )
   {

    return sum;
   }
  }
 }
 return sum;
}