Program

#include<stdio.h>

long fact(int);
int main(){
    int line,i,j;

    printf("Enter the no. of lines: ");
    scanf("%d",&line);

    for(i=0;i<line;i++){
         for(j=0;j<line-i-1;j++)
             printf(" ");

         for(j=0;j<=i;j++)
             printf("%ld ",fact(i)/(fact(j)*fact(i-j)));
         printf("\n");
    }
    return 0;
}

long fact(int num){
    long f=1;
    int i=1;
    while(i<=num){
         f=f*i;
         i++;
  }
  return f;
 }

Result

Enter the no. of lines: 8
       1
      1 1
     1 2 1
    1 3 3 1
   1 4 6 4 1
  1 5 10 10 5 1
 1 6 15 20 15 6 1
1 7 21 35 35 21 7 1