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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 10 |
| 6 | 32 |
| 7 | 105 |
| 8 | 356 |
| 9 | 1227 |
| 10 | 4327 |
| 11 | 15444 |
| 12 | 55830 |
| 13 | 203785 |
| 14 | 750388 |
| 15 | 2783465 |
| 16 | 10392923 |
| 17 | 39027561 |
| 18 | 147308309 |
| 19 | 558550110 |
| 20 | 2126574259 |
| 21 | 8126608112 |
| 22 | 31160297271 |
| 23 | 119847314043 |
| 24 | 462250371050 |
| 25 | 1787514078393 |
| 26 | 6928792593819 |
| 27 | 26916827827548 |
| 28 | 104780189202901 |
[0,1,1,1,4,10,32,105,356,1227,4327,15444,55830, 203785,750388,2783465,10392923,39027561,147308309, 558550110,2126574259,8126608112,31160297271, 119847314043,462250371050,1787514078393, 6928792593819,26916827827548,104780189202901] |