Numerateurs:Denominateurs                                                                           
                                                                                                                        
                    1:1   1:2---1:3   1:4---1:5   (...)                                                                 
                     |    /     /     /     /                                                                           
                     |  /     /     /     /                                                                             
                     |/     /     /     /                                                                               
                    2:1   2:2   2:3   2:4   2:5   (...)                                                                 
                          /     /     /                                                                                 
                        /     /     /                                                                                   
                      /     /     /                                                                                     
                    3:1   3:2   3:3   3:4   3:5   (...)                                                                 
                     |    /     /                                                                                       
                     |  /     /                                                                                         
                     |/     /                                                                                           
                    4:1   4:2   4:3   4:4   4:5   (...)                                                                 
                          /                                                                                             
                        /    (...)                                                                                      
                      /     /                                                                                           
                    5:1   5:2   5:3   5:4   5:5   (...)                                                                 
                     |    / .     .     .     .                                                                         
                     |  /   .     .     .     .                                                                         
                     |/     .     .     .     .                                                                         
                                                                                                                        
                    (...)                                                                                               
                                                                                                                        
                                                                                                                        
                                                                                                                        
                    {1/1, 2/1, 1/2, 1/3, 2/2, 3/1, 4/1, 3/2, 2/3, 1/4, 1/5, 2/4, 3/3, 4/2, 5/1, 5/2,...   }             
                      |    |    |         |                                  |    |    |                                
                      |-------------------                                   |    |    |                                
                      |    |    |                                            |    |    |                                
                      |    |     --------------------------------------------     |    |                                
                      |    |                                                      |    |                                
                       -----------------------------------------------------------     |                                
                           |                                                           |                                
                            -----------------------------------------------------------                                 
                                                                                                                        
                     -------------------------------------------------------------------------------------              
                    |                                                                                     |             
                    |  1/1  2/1  1/2  1/3       3/1  4/1  3/2  2/3  1/4  1/5                 5/1  5/2 ... |             
                    |   |    |    |    |         |    |    |    |    |    |                   |    |      |             
                     -------------------------------------------------------------------------------------              
                        |    |    |    |         |    |    |    |    |    |                   |    |                    
                        |    |    |    |         |    |    |    |    |    |                   |    |                    
                        |    |    |    |         |    |    |    |    |    |                   |    |                    
                     -------------------------------------------------------------------------------------              
                    |   |    |    |    |         |    |    |    |    |    |                   |    |      |             
                    |   1    2    3    4         5    6    7    8    9   10                  11   12 ...  |             
                    |                                                                                     |             
                     -------------------------------------------------------------------------------------              
                                                                                                                        
                                                                                                                        
 JFC                                                                                                                    
 www.lactamme.polytechnique.fr