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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 62 |
| 6 | 209 |
| 7 | 722 |
| 8 | 2539 |
| 9 | 9054 |
| 10 | 32654 |
| 11 | 118876 |
| 12 | 436171 |
| 13 | 1611067 |
| 14 | 5984943 |
| 15 | 22344455 |
| 16 | 83786875 |
| 17 | 315397144 |
| 18 | 1191324649 |
| 19 | 4513742858 |
| 20 | 17149228138 |
| 21 | 65318912291 |
| 22 | 249356597492 |
| 23 | 953902701488 |
| 24 | 3656057618727 |
| 25 | 14037222220896 |
[1,1,2,6,19,62,209,722,2539,9054,32654,118876, 436171,1611067,5984943,22344455,83786875, 315397144,1191324649,4513742858,17149228138, 65318912291,249356597492,953902701488, 3656057618727,14037222220896] |