# A006780 (b-file synthesized from sequence entry)
0 1
1 6
2 24
3 90
4 324
5 1166
6 4138
7 14730
8 51992
9 183898
10 646980
11 2279702
12 8002976
13 28127418
14 98585096
15 345848306
16 1210704274
17 4241348770
18 14833284544
19 51907058582
20 181392476966
21 634197818374
22 2214804822718
23 7737946227490