# A247212 (b-file synthesized from sequence entry) 0 1 1 1 2 0 3 6 4 12 5 -20 6 420 7 -252 8 -336 9 66960 10 -368640 11 2328480 12 2898720 13 -117767520 14 1720764864 15 -12297479040 16 58230547200 17 312819736320 18 -9239378296320 19 128087696977920 20 -1154590730496000 21 7050771080478720 22 398679450301440 23 -591762353886950400 24 6580219687752775680