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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 4 |
| 5 | 7 |
| 6 | 16 |
| 7 | 38 |
| 8 | 97 |
| 9 | 257 |
| 10 | 704 |
| 11 | 1985 |
| 12 | 5742 |
| 13 | 17013 |
| 14 | 51532 |
| 15 | 159356 |
| 16 | 502470 |
| 17 | 1613880 |
| 18 | 5275917 |
| 19 | 17543426 |
| 20 | 59307258 |
| 21 | 203759160 |
| 22 | 711246902 |
| 23 | 2521876015 |
| 24 | 9081377033 |
| 25 | 33207738613 |
| 26 | 123289411854 |
| 27 | 464675856111 |
| 28 | 1777656126662 |
| 29 | 6901581699899 |
| 30 | 27187917004378 |
[1,1,2,2,4,7,16,38,97,257,704,1985,5742,17013, 51532,159356,502470,1613880,5275917,17543426, 59307258,203759160,711246902,2521876015, 9081377033,33207738613,123289411854,464675856111, 1777656126662,6901581699899,27187917004378] |