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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 27 |
| 5 | 110 |
| 6 | 428 |
| 7 | 1624 |
| 8 | 6069 |
| 9 | 22458 |
| 10 | 82555 |
| 11 | 302082 |
| 12 | 1101816 |
| 13 | 4009616 |
| 14 | 14567657 |
| 15 | 52865230 |
| 16 | 191684283 |
| 17 | 694609494 |
| 18 | 2515972324 |
| 19 | 9110338728 |
| 20 | 32981059485 |
| 21 | 119377761602 |
| 22 | 432046756571 |
| 23 | 1563510554986 |
| 24 | 5657752486512 |
| 25 | 20472344560800 |
[1,6,27,110,428,1624,6069,22458,82555,302082, 1101816,4009616,14567657,52865230,191684283, 694609494,2515972324,9110338728,32981059485, 119377761602,432046756571,1563510554986, 5657752486512,20472344560800] |