# A006568 (b-file synthesized from sequence entry)
0 1
1 3
2 18
3 90
4 270
5 1134
6 5670
7 2430
8 7290
9 133650
10 112266
11 1990170
12 9950850
13 2296350
14 984150
15 117113850
16 351341550
17 33657930
18 21597171750
19 3410079750
20 572893398
21 33613643250
22 834229509750
23 108812544750
24 544062723750
25 18280507518
26 105464466450
27 18690647109750