#!/bin/bash

LIMIT=20  # Superior limit

echo "Print the numbers between 1 and 20 (with the exclusion of the numbers 4 and 13)."

a=0

while [ $a -lt "$LIMIT" ]
do
    a=$(($a+1))
    # a=$[$a+1] # Another possible way to compute mathematical operations

    if [ "$a" -eq 4 ] || [ "$a" -eq 13 ]  # Exclusion of 4 and 13 numbers
    then
        continue  # Skip the rest of this cycle
    fi
    
    echo -n "$a "
done 
echo # Print new line

exit 0