# A009357 (b-file synthesized from sequence entry) 0 0 1 1 2 -1 3 0 4 2 5 -20 6 104 7 -560 8 2512 9 -7920 10 -32896 11 1034880 12 -14979328 13 172569280 14 -1684304896 15 12339608320 16 -15173408768 17 -1902800305920 18 53242752303104 19 -1037015219466240 20 16518488951816192 21 -208832669083243520