Bash for loop example-1

#!/bin/bash
 # Usage: script.sh number
# A for loop example produces following output
#
#             *
#          *     *
#       *     *     *
#    *     *     *     *
# *     *     *     *     *
#
Method1
c=1
n=$1
echo -e "\033[47m\c"  #colourizing output
for ((row=1;row<=n;row++))
do
        for ((i=row;i<n;i++))
        do
                echo -n '   '
        done
        for ((k=1;k<=c;k++))
        do
           if [ $((k%2)) -eq 0 ]
           then
             echo -n "   "
           else
             echo -e "\033[43m * \033[47m\c"
           fi
        done
        for ((i=row;i<n;i++))
        do
                echo -n '   '
        done
 c=$((c+2))
        echo
done
echo -e "\033[0m"   #Restoring colours
unset c i k n row
Method2
#!/bin/bash
n=$1
t=$((2*n - 1 ))
a=$n
b=$((a+1))
echo -e -n "\033[47m"
for (( i=1 ; i<=$n ;i++ ))
do
  a=$(($b-1))
  b=$a
  k=1
  for (( j=1 ; j<=$t ; j++ ))
  do
      if [ $j -eq $a ]
      then

         echo -e "\033[43m * \033[47m\c"
         if [ $k -lt $i ]
         then

            a=$((a+2))
   let k++
         fi
      else
         echo -n "   "
     fi

  done
echo
done
echo -e "\033[0m"

Output: