a(n,m) tabf head (staircase) for A090438 (from Blasiak et al ref. for r=4, s=2) 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 12 8 1 0 0 0 0 0 0 0 0 3 360 480 180 24 1 0 0 0 0 0 0 4 20160 40320 25200 6720 840 48 1 0 0 0 0 5 1814400 4838400 4233600 1693440 352800 40320 2520 80 1 0 0 6 239500800 798336000 898128000 479001600 139708800 23950080 2494800 158400 5940 120 1 The sequence of row length for this tabf array is [1,3,5,7,9,11,...]=A005408(n-1), n>=1.