Pascal Triangle

#! /bin/bash

calcElement(){
    num=1
    for(( a=$i; a>1; a-- )){
        let num*=a
    }

    den1=1
    for(( a=$j; a>1; a-- )){
        let den1*=a
    }

    den2=1
    for(( a=$i-$j; a>1; a-- )){
        let den2*=a
    }

    ans=$(( num / (den1*den2) ))
}

echo -n "Enter the number of rows: "
read n

for(( i=0; i<$n; i++ )){
    for(( space=$n-$i-1; space>=0; space-- )){
        echo -n " "
    }
    for(( j=0; j<=i; j++ )){
        calcElement
        echo -n "$ans "
    }
    echo ""
}