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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 56 |
| 6 | 288 |
| 7 | 1583 |
| 8 | 9129 |
| 9 | 54578 |
| 10 | 335522 |
| 11 | 2108754 |
| 12 | 13492814 |
| 13 | 87615489 |
| 14 | 575986999 |
| 15 | 3826311988 |
| 16 | 25646949717 |
| 17 | 173243532072 |
| 18 | 1178199786364 |
| 19 | 8060658132743 |
| 20 | 55439470986851 |
| 21 | 383105416597112 |
| 22 | 2658636183714792 |
| 23 | 18520888690187382 |
| 24 | 129471023915349560 |
[0,1,1,3,12,56,288,1583,9129,54578,335522,2108754, 13492814,87615489,575986999,3826311988, 25646949717,173243532072,1178199786364, 8060658132743,55439470986851,383105416597112, 2658636183714792,18520888690187382, 129471023915349560] |