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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 10 |
| 3 | 44 |
| 4 | 186 |
| 5 | 772 |
| 6 | 3172 |
| 7 | 12952 |
| 8 | 52666 |
| 9 | 213524 |
| 10 | 863820 |
| 11 | 3488872 |
| 12 | 14073060 |
| 13 | 56708264 |
| 14 | 228318856 |
| 15 | 918624304 |
| 16 | 3693886906 |
| 17 | 14846262964 |
| 18 | 59644341436 |
| 19 | 239532643144 |
| 20 | 961665098956 |
| 21 | 3859788636664 |
| 22 | 15488087080696 |
| 23 | 62135313450064 |
[0,2,10,44,186,772,3172,12952,52666,213524,863820, 3488872,14073060,56708264,228318856,918624304, 3693886906,14846262964,59644341436,239532643144, 961665098956,3859788636664,15488087080696, 62135313450064] |