# A002490 (b-file synthesized from sequence entry)
0 1
1 0
2 2
3 1652
4 119550
5 1497328
6 16733124
7 108084480
8 588808172
9 2544811584
10 9516509988
11 31328336284
12 92876219432
13 252846150384
14 638250041288
15 1511780647680
16 3387237676950
17 7228330859840
18 14769380958438
19 29023337216604
20 55108233751768
21 101433859301088