<form action="">
    <input type="number" name="number1">
    <input type="submit" name="Bangladesh">
</form>
<?php
    if(isset($_GET['Bangladesh'])){
        $number1=$_GET['number1'];
        $number1;
        for($start=1; $start<=100; $start=$start+2){
            echo "$start";
        }
        echo"<br>";

        for($start=1; $start<=$number1; $start=$start+2){
            echo "$start";
        }
    }
?>