# A012480 (b-file synthesized from sequence entry)
0 1
1 1
2 1
3 -1
4 -7
5 -15
6 25
7 359
8 1297
9 3713
10 785
11 347151
12 3237577
13 62839153
14 476552297
15 10196506423
16 93536269473
17 2397571040897
18 25410713978785
19 714196911010335
20 8498142387238425
21 263318643848985457