Codeignater.pagination 404 error?

Question

PHP

Problem: I'm learning a framework. server - openserver. Testing the pagination class. The code is described below. As a result of opening www1/index.php/welcome/articles , the first entry opens, everything is as it should be, links are created ( < 1 2 3 Next > ), but any other link does not work. (i.e. only the first one works, which is opened immediately in the direction of the articles function of the welcome controller). When you click on link number 2, for example, you get the address localhost/index.php/welcome/articles/1 and eror 404, so with all other linksb. How to make links work?
Controller :
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class Welcome extends CI_Controller
{
public function index()
{
echo "this is index";
}
public function articles()
{
$this->load->library('pagination');
$config['base_url'] = ' localhost/index.php/welcome/articles ';
$config['total_rows'] = $this->db->count_all('books');
$config['per_page'] = 1;
$config['full_tag_open'] = '';
$config['full_tag_close'] = '';
$this->pagination->initialize($config);
$this->load->model('get_db');
$data['artic'] = $this->get_db->get_dbb($config['per_page'],$this->uri->segment(3));
$this->load->view('all_books', $data);
defined('BASEPATH') OR exit('No direct script access allowed');
class get_db extends CI_Model {
public function get_dbb($num, $offset)
{
$this->db->order_by('id','desc');
$query = $this->db->get('books',$num, $offset);
return $query->result_array();
}
}
View:
it makes no sense to expose the code. there is
<?php echo $this->pagination->create_links();?>