# A009806 (b-file synthesized from sequence entry)
0 0
1 1
2 -1
3 2
4 -6
5 16
6 0
7 -792
8 13776
9 -200552
10 2855880
11 -41436352
12 620388912
13 -9606956592
14 153409074000
15 -2508503487232
16 41503122145920
17 -680444083117184
18 10600133081473152
19 -140189781816392448
20 819083424632851200