# A005768 (b-file synthesized from sequence entry)
2 1
3 2
4 7
5 27
6 110
7 460
8 1948
9 8296
10 35400
11 151056
12 643892
13 2740216
14 11639416
15 49340080
16 208727176
17 881212272
18 3713043152
19 15615663008
20 65555425780
21 274734294328
22 1149506252376
23 4802212126704
24 20032666552664
25 83452195924304
26 347192769717040
27 1442672957396320