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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 26 |
| 4 | 106 |
| 5 | 452 |
| 6 | 1999 |
| 7 | 9074 |
| 8 | 42046 |
| 9 | 198044 |
| 10 | 945430 |
| 11 | 4564100 |
| 12 | 22243060 |
| 13 | 109285256 |
| 14 | 540738943 |
| 15 | 2692103714 |
| 16 | 13475973238 |
| 17 | 67784600108 |
| 18 | 342439638418 |
| 19 | 1736727343436 |
| 20 | 8839203054604 |
| 21 | 45132514680248 |
| 22 | 231121351433158 |
[1,2,7,26,106,452,1999,9074,42046,198044,945430, 4564100,22243060,109285256,540738943,2692103714, 13475973238,67784600108,342439638418, 1736727343436,8839203054604,45132514680248, 231121351433158] |