// pagination for custom page(s)
$paged = (get_query_var('page')) ? get_query_var('page') : 1;

//query args
$idObj1 = get_category_by_slug('updates');
$catid1 = $idObj1->term_id;
$args1 = array(
    'order'                 => 'DESC',
    'post_status'           => 'publish',
    'cat'                   => $catid1,
    'paged'                 => $paged
);

if(!is_paged()) {
  $args1['posts_per_page'] = 9;
} else {
  $args1['posts_per_page'] = 18;
  $offset = 9 + (18*($paged-2));
  $args1['offset'] = $offset;
}

query_posts($args1);