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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 5 |
| 5 | 9 |
| 6 | 26 |
| 7 | 66 |
| 8 | 199 |
| 9 | 575 |
| 10 | 1790 |
| 11 | 5542 |
| 12 | 17945 |
| 13 | 58733 |
| 14 | 198880 |
| 15 | 685296 |
| 16 | 2429281 |
| 17 | 8778321 |
| 18 | 32491940 |
| 19 | 122503412 |
| 20 | 471379771 |
| 21 | 1844669495 |
| 22 | 7346727298 |
| 23 | 29712688698 |
| 24 | 122054603983 |
| 25 | 508548201863 |
| 26 | 2149211636944 |
| 27 | 9204566602696 |
| 28 | 39944636660655 |
[1,1,2,2,5,9,26,66,199,575,1790,5542,17945,58733, 198880,685296,2429281,8778321,32491940,122503412, 471379771,1844669495,7346727298,29712688698, 122054603983,508548201863,2149211636944, 9204566602696,39944636660655] |