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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 34 |
| 6 | 117 |
| 7 | 385 |
| 8 | 1432 |
| 9 | 5160 |
| 10 | 20168 |
| 11 | 77045 |
| 12 | 311677 |
| 13 | 1239448 |
| 14 | 5140477 |
| 15 | 21049400 |
| 16 | 88974654 |
| 17 | 372438423 |
| 18 | 1597803426 |
| 19 | 6803880625 |
| 20 | 29540393405 |
| 21 | 127517380748 |
| 22 | 559088380312 |
| 23 | 2440361663214 |
| 24 | 10787438980198 |
| 25 | 47519879806761 |
| 26 | 211517358073448 |
| 27 | 938964601279267 |
| 28 | 4204355678918899 |
[1,1,2,4,12,34,117,385,1432,5160,20168,77045, 311677,1239448,5140477,21049400,88974654, 372438423,1597803426,6803880625,29540393405, 127517380748,559088380312,2440361663214, 10787438980198,47519879806761,211517358073448, 938964601279267,4204355678918899] |