# A024330 (b-file synthesized from sequence entry) 0 0 1 0 2 1 3 -3 4 7 5 -10 6 -18 7 168 8 360 9 -19008 10 262080 11 -2724480 12 25194240 13 -232951680 14 2505444480 15 -34676812800 16 577980748800 17 -10296734515200 18 185178186547200 19 -3347775973785600 20 62005095419904000 21 -1204098364514304000