Shell Script To Print Pyramid-Using for Loop

#!/bin/bash
# Usage: scriptname argument
# Here argument is height of pyramid
# Output would be pyramid pattern of stars

#       0                 *
#       1                ***
#       2               *****
#       3              *******
#       4             *********
#       5            ***********
#       6           *************
#       .          ***************
#       .         *****************
#       .        *******************
#      n-1     *********************
#                ---\/--- | ---\/---
#                  n - 1      n - 1
#

clear
n=$1
echo -e "\033[47m"  #used for colourizing output
for ((row=1;row<=n;row++)) 
do
    spaces=$((n-row))
    stars=$((2*$row - 1))
    for ((i=1;i<=spaces;i++))
    do
        echo -n ' '
    done 
    for ((i=1;i<=stars;i++))
    do 
        echo -e '\033[43m*\033[47m\c'
    done
    for ((i=1;i<=spaces;i++))
    do  
         echo -n ' ' 
    done
    echo
done
echo -e "\033[0m"
unset n i spaces stars row
# Unset variables is a good programming practice 

Output:
[root@localhost blog]# sh for_pyramid 22