F1 rule: checked 2 <= D <= 16: 0 failures
# F1 tiling of (21,27): R = right stone, V/S/F = bones
  15     SSS                        
  14    SSSSSS                      
  13   SSSSSSSSS                    
  12  SSSSSSSSSSSS                  
  11 SSSSSSSSSSSSSSS                
  10  FSSSSSSSSSSSSSSS              
   9  FFFSSSSSSSSSSSSSSS            
   8   FFFFSSSSSSSSSSSSSSS          
   7   FFFFFFSSSSSSSSSSSSSSS        
   6    FFFFFFFSSSSSSSSSSSSSSS      
   5    FFFFFFFFSSSSSSSSSSSSSSSV    
   4     FFFFFFFFRSSSSSSSSSSSSVV    
   3     FFFFFFFFRRRSSSSSSSSSVVVV   
   2      FFFFFFFFRRRRSSSSSSVVVVV   
   1      FFFFFFFFRRRRRRSSSVVVVVVV  
   0       FFFFFFFFRRRRRRVVVVVVVVV  
  -1       FFFFFFFFRRRRRVVVVVVVVVVV 
  -2        FFFFFFFFRRRVVVVVVVVVVVV 
  -3        FFFFFFFFRRVVVVVVVVVVVVVV
  -4         FFFFFFFFVVVVVVVVVVVVVVV
  -5         FFFFFFFFVVVVVVVVVVVVVVV
  -6          FFFFFFFVVVVVVVVVVVVVV 
  -7          FFFFFFFFVVVVVVVVVVVV  
  -8           FFFFFFFVVVVVVVVVVV   
  -9           FFFFFFFFVVVVVVVVV    
 -10            FFFFFFFVVVVVVVV     
 -11             FFFFFFFVVVVVV      
 -12               FFFFFVVVVV       
 -13                 FFFFVVV        
 -14                   FFVV         
 -15                     F          
