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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 16 |
| 4 | 50 |
| 5 | 156 |
| 6 | 532 |
| 7 | 1856 |
| 8 | 6876 |
| 9 | 26200 |
| 10 | 104456 |
| 11 | 428352 |
| 12 | 1821976 |
| 13 | 7959056 |
| 14 | 35857200 |
| 15 | 165592576 |
| 16 | 785514512 |
| 17 | 3812387616 |
| 18 | 18948962656 |
| 19 | 96194028800 |
| 20 | 498931946016 |
| 21 | 2638959243712 |
| 22 | 14234346694976 |
[1,2,6,16,50,156,532,1856,6876,26200,104456, 428352,1821976,7959056,35857200,165592576, 785514512,3812387616,18948962656,96194028800, 498931946016,2638959243712,14234346694976] |