# A137958 (b-file synthesized from sequence entry)
0 1
1 1
2 4
3 18
4 100
5 587
6 3660
7 23640
8 157076
9 1066281
10 7363620
11 51568732
12 365369868
13 2614235293
14 18862816112
15 137096744232
16 1002785827620
17 7376023180645
18 54525165453672
19 404858512190316
20 3018190533410664
21 22581907465905018