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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 12 |
| 5 | 44 |
| 6 | 116 |
| 7 | 374 |
| 8 | 1428 |
| 9 | 5960 |
| 10 | 26016 |
| 11 | 120570 |
| 12 | 590598 |
| 13 | 3065372 |
| 14 | 16566508 |
| 15 | 92827128 |
| 16 | 542485764 |
| 17 | 3298228302 |
| 18 | 20696614200 |
| 19 | 133722820270 |
| 20 | 892046755174 |
| 21 | 6136788856858 |
| 22 | 43308637312440 |
| 23 | 313079705562778 |
| 24 | 2322726645160856 |
[1,1,2,6,12,44,116,374,1428,5960,26016,120570, 590598,3065372,16566508,92827128,542485764, 3298228302,20696614200,133722820270,892046755174, 6136788856858,43308637312440,313079705562778, 2322726645160856] |