# A009711 (b-file synthesized from sequence entry)
0 0
1 1
2 -1
3 2
4 -6
5 16
6 0
7 -568
8 7504
9 -78248
10 739080
11 -6314848
12 44072688
13 -125928464
14 -3754236304
15 114500663552
16 -2264653307520
17 37495468333696
18 -536284797406848
19 6159440282136320
20 -34551694794080000
21 -931439976890484224