catalog/page-n/

function __isPathTraversalUri($uri) {
 if (($pos = strpos($uri, '?')) !== false) {
 $uri = substr($uri, 0, $pos);
 }
 
 $uri = trim($uri);
 
 return preg_match("#(?:/|2f|^|\\\\|5c)(??:%0*(25)*2e)|\\.){2,}(?:/|%0*(25)*2f|\\\\|%0*(25)*5c|$)#i", $uri) ? true : false;
}

$newUri = preg_replace('#(page-[\d]+/)#is', '', $_SERVER['REQUEST_URI']

if (!__isPathTraversalUri($newUri)) {
 $_SERVER['REQUEST_URI'] = $newUri;
}

<IfModule mod_rewrite.c>
   Options +FollowSymLinks
 RewriteEngine On


 php_value auto_prepend_file "path to /bitrix/pagen.php"
    #RewriteRule ^(.*)page-1(.)$ /$1 [R=301,L]
 RewriteRule ^(.*)/page-([\d]+)/ /$1/?PAGEN_1=$2 [L,QSA]

 # Проверяем, повторяется ли слеш (//) более двух раз.
 RewriteCond %{REQUEST_URI} ^(.*)/{2,}(.*)$
 # Исключаем все лишние слеши
 RewriteRule . %1/%2 [R=301,L]

 RewriteCond %{REQUEST_FILENAME} !-f
 RewriteCond %{REQUEST_FILENAME} !-l
 RewriteCond %{REQUEST_FILENAME} !-d
 RewriteCond %{REQUEST_FILENAME} !/bitrix/urlrewrite.php$
 RewriteRule ^(.*)$ /bitrix/urlrewrite.php [L]
 RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization}]

 #Rewrite from www to host
 RewriteCond %{HTTP_HOST} ^www\.(.*) [NC]
 RewriteRule ^(.*)$ http://%1/$1 [R=301,L]

</IfModule>