# A181997 (b-file synthesized from sequence entry)
0 1
1 1
2 2
3 9
4 46
5 259
6 1539
7 9484
8 59961
9 386319
10 2524940
11 16687599
12 111264335
13 747080253
14 5044629212
15 34218868880
16 232964088130
17 1590660486297
18 10885758313976
19 74627209920879
20 512254418843196
21 3519150502675731
22 24187028454513735
23 166249089897708930