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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 21 |
| 5 | 48 |
| 6 | 108 |
| 7 | 243 |
| 8 | 549 |
| 9 | 1242 |
| 10 | 2808 |
| 11 | 6345 |
| 12 | 14337 |
| 13 | 32400 |
| 14 | 73224 |
| 15 | 165483 |
| 16 | 373977 |
| 17 | 845154 |
| 18 | 1909980 |
| 19 | 4316409 |
| 20 | 9754749 |
| 21 | 22044960 |
| 22 | 49819860 |
| 23 | 112588947 |
| 24 | 254442141 |
| 25 | 575019162 |
| 26 | 1299497904 |
| 27 | 2936762649 |
| 28 | 6636851721 |
| 29 | 14998760928 |
[1,2,4,9,21,48,108,243,549,1242,2808,6345,14337, 32400,73224,165483,373977,845154,1909980,4316409, 9754749,22044960,49819860,112588947,254442141, 575019162,1299497904,2936762649,6636851721, 14998760928] |