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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 36 |
| 4 | 172 |
| 5 | 860 |
| 6 | 4460 |
| 7 | 23820 |
| 8 | 130268 |
| 9 | 726236 |
| 10 | 4112972 |
| 11 | 23599724 |
| 12 | 136906748 |
| 13 | 801671996 |
| 14 | 4732110828 |
| 15 | 28128179276 |
| 16 | 168222049052 |
| 17 | 1011509012636 |
| 18 | 6111445499532 |
| 19 | 37084090264364 |
| 20 | 225899543897916 |
| 21 | 1380918157453052 |
| 22 | 8468524718133804 |
| 23 | 52085281291575052 |
[1,2,8,36,172,860,4460,23820,130268,726236, 4112972,23599724,136906748,801671996,4732110828, 28128179276,168222049052,1011509012636, 6111445499532,37084090264364,225899543897916, 1380918157453052,8468524718133804, 52085281291575052] |