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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 27 |
| 6 | 80 |
| 7 | 230 |
| 8 | 719 |
| 9 | 2271 |
| 10 | 7519 |
| 11 | 25425 |
| 12 | 88868 |
| 13 | 317972 |
| 14 | 1168360 |
| 15 | 4392724 |
| 16 | 16903393 |
| 17 | 66463148 |
| 18 | 266897917 |
| 19 | 1093550522 |
| 20 | 4568688612 |
| 21 | 19448642187 |
| 22 | 84308851083 |
| 23 | 371950915996 |
| 24 | 1669146381915 |
| 25 | 7615141902820 |
| 26 | 35304535554923 |
| 27 | 166248356878549 |
| 28 | 794832704948402 |
| 29 | 3856672543264073 |
| 30 | 18984761300310500 |
[1,1,2,4,11,27,80,230,719,2271,7519,25425,88868, 317972,1168360,4392724,16903393,66463148, 266897917,1093550522,4568688612,19448642187, 84308851083,371950915996,1669146381915, 7615141902820,35304535554923,166248356878549, 794832704948402,3856672543264073, 18984761300310500] |