#!/bin/bash
# numbers to start with
COUNT=1 
XVALUE=1 

while [ $COUNT -lt 400 ]; do

if [ $COUNT -lt 200 ]; then
let XVALUE=XVALUE+1

elif [ $COUNT -ge 200 ]; then
let XVALUE=XVALUE-1  

fi

let COUNT=COUNT+1

echo $XVALUE 

done