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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 16 |
| 6 | 45 |
| 7 | 138 |
| 8 | 439 |
| 9 | 1417 |
| 10 | 4698 |
| 11 | 16021 |
| 12 | 55146 |
| 13 | 190274 |
| 14 | 671224 |
| 15 | 2404289 |
| 16 | 8535117 |
| 17 | 30635869 |
| 18 | 110496946 |
| 19 | 401422210 |
| 20 | 1467402238 |
| 21 | 5393176633 |
| 22 | 19883249002 |
| 23 | 73856531314 |
| 24 | 273602448261 |
| 25 | 1017563027699 |
| 26 | 3803902663467 |
| 27 | 14266523388813 |
| 28 | 53564969402478 |
[1,1,3,6,16,45,138,439,1417,4698,16021,55146, 190274,671224,2404289,8535117,30635869,110496946, 401422210,1467402238,5393176633,19883249002, 73856531314,273602448261,1017563027699, 3803902663467,14266523388813,53564969402478] |