wp_update_network_site_counts( int|null $network_id = null )

function wp_update_network_site_counts( $network_id = null ) {
	$network_id = (int) $network_id;
	if ( ! $network_id ) {
		$network_id = get_current_network_id();
	}

	$count = get_sites( array(
		'network_id' => $network_id,
		'spam'       => 0,
		'deleted'    => 0,
		'archived'   => 0,
		'count'      => true,
	) );

	update_network_option( $network_id, 'blog_count', $count );
}