a(n,m) tabl head (triangle) for A090217 n\m 1 2 3 4 5 6 7 8 1 1 0 0 0 0 0 0 0 2 120 1 0 0 0 0 0 0 3 14400 840 1 0 0 0 0 0 4 1728000 619200 3360 1 0 0 0 0 5 207360000 447552000 9086400 10080 1 0 0 0 6 24883200000 322444800000 23345280000 76824000 25200 1 0 0 7 2985984000000 232185139200000 59152550400000 539602560000 457848000 55440 1 0 8 358318080000000 167176286208000000 149296612147200000 3685281753600000 7462264320000 2134353600 110880 1