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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 15 |
| 6 | 105 |
| 7 | 855 |
| 8 | 7855 |
| 9 | 58915 |
| 10 | 642385 |
| 11 | 9004755 |
| 12 | 115824435 |
| 13 | 1604808065 |
| 14 | 25144782705 |
| 15 | 455128178085 |
| 16 | 8168562081915 |
| 17 | 158166596302055 |
| 18 | 3295573475438405 |
| 19 | 73982086933664855 |
| 20 | 1712715517531862335 |
| 21 | 41970840045144861565 |
| 22 | 1087768715565961794905 |
[1,1,1,7,15,105,855,7855,58915,642385,9004755, 115824435,1604808065,25144782705,455128178085, 8168562081915,158166596302055,3295573475438405, 73982086933664855,1712715517531862335, 41970840045144861565,1087768715565961794905] |