a(n,k)  tabf head (staircase) for  A091747

  
     n\k           2             3             4            5           6          7          8       9     10     11     12

                      
     1             1             0             0            0           0          0          0       0      0      0      0
                        
     2            42            14             1            0           0          0          0       0      0      0      0
                      
     3          5544          3192           588           42           1          0          0       0      0      0      0
                      
     4       1507968       1165248        321552        41496        2688         84          1       0      0      0      0
                    
     5     696681216     655966080     232606080    414973444      143552     240240       7980     140      1      0      0
       
     6  489070213632  533531142144  226306918656  50249808000  6575950080  536715648   27945792  924000  18690    210      1

  
     The sequence of row lengths for this array is [1,3,5,7,9,11,...]=A005408(n-1), n>=1.