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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 3 |
| 5 | 6 |
| 6 | 18 |
| 7 | 42 |
| 8 | 105 |
| 9 | 291 |
| 10 | 792 |
| 11 | 2181 |
| 12 | 6177 |
| 13 | 17628 |
| 14 | 50679 |
| 15 | 147255 |
| 16 | 430917 |
| 17 | 1268292 |
| 18 | 3754926 |
| 19 | 11172828 |
| 20 | 33389040 |
| 21 | 100181994 |
| 22 | 301682709 |
| 23 | 911436117 |
| 24 | 2761852011 |
| 25 | 8392005462 |
| 26 | 25563691341 |
| 27 | 78053071611 |
| 28 | 238830914937 |
| 29 | 732247187460 |
| 30 | 2249217635238 |
[1,1,3,3,6,18,42,105,291,792,2181,6177,17628, 50679,147255,430917,1268292,3754926,11172828, 33389040,100181994,301682709,911436117,2761852011, 8392005462,25563691341,78053071611,238830914937, 732247187460,2249217635238] |