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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 14 |
| 5 | 52 |
| 6 | 205 |
| 7 | 832 |
| 8 | 3492 |
| 9 | 14960 |
| 10 | 65322 |
| 11 | 289384 |
| 12 | 1298064 |
| 13 | 5882712 |
| 14 | 26897352 |
| 15 | 123919576 |
| 16 | 574718308 |
| 17 | 2681028168 |
| 18 | 12571650355 |
| 19 | 59222213028 |
| 20 | 280139215118 |
| 21 | 1330101884932 |
| 22 | 6336757979653 |
| 23 | 30282375754944 |
| 24 | 145124083402256 |
| 25 | 697293746743760 |
| 26 | 3358385599930269 |
| 27 | 16210842955175380 |
[1,1,4,14,52,205,832,3492,14960,65322,289384, 1298064,5882712,26897352,123919576,574718308, 2681028168,12571650355,59222213028,280139215118, 1330101884932,6336757979653,30282375754944, 145124083402256,697293746743760,3358385599930269, 16210842955175380] |