Form to redirect to a particular URL

header('location:  http://staticurl/'.$_POST['number'].'html');

Maybe?

Assume a HTML form like

<form action="" method="POST">
    <input type="number" name="number">
    <input type="submit" name="submit" value="submit">
</form>

Now using php you can redirect

<?php 
    if(isset($_POST['submit'])){
        header("Location: http://staticurl/".$_POST['number'].".html");
    }
 ?>

If header() returns any error then you can do it with javascript inside php like

<?php 
    if(isset($_POST['submit'])){
        echo '
            <script>
                window.location.href = "http://staticurl/'.$_POST['number'].'.html";
            </script>
        ';
    }
 ?>

Validate the form data before processing it.