# A019221 (b-file synthesized from sequence entry)
3 1
4 1
5 1
6 0
7 0
8 8
9 24
10 90
11 240
12 492
13 1064
14 2452
15 5814
16 14766
17 38400
18 98846
19 252902
20 644456
21 1641944
22 4201380
23 10802792
24 27907392
25 72395562
26 188325960
27 491013312
28 1283101256
29 3359669780
30 8813687070
31 23166783438