a(n,m) tabl head (triangle) for A090441 n\m 0 1 2 3 4 5 6 7 8 9 -1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 2 1 2 2 1 0 0 0 0 0 0 3 1 6 12 6 1 0 0 0 0 0 4 1 24 144 144 24 1 0 0 0 0 5 1 120 2880 8640 2880 120 1 0 0 0 6 1 720 86400 1036800 1036800 86400 720 1 0 0 7 1 5040 3628800 217728000 870912000 217728000 3628800 5040 1 0 8 1 40320 203212800 73156608000 1463132160000 1463132160000 73156608000 203212800 40320 1