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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 8 |
| 3 | 22 |
| 4 | 368 |
| 5 | 2470 |
| 6 | 7880 |
| 7 | 150266 |
| 8 | 13315424 |
| 9 | 2350261538 |
| 10 | 1777792792 |
| 11 | 340013628538 |
| 12 | 203832594062416 |
| 13 | 131294440969788022 |
| 14 | 822860039794822168 |
| 15 | 177175812995012739374 |
| 16 | 231553634961214157747264 |
| 17 | 1813465925343969651214825522 |
| 18 | 14983458468103810854318443432 |
[0,2,8,22,368,2470,7880,150266,13315424, 2350261538,1777792792,340013628538, 203832594062416,131294440969788022, 822860039794822168,177175812995012739374, 231553634961214157747264, 1813465925343969651214825522, 14983458468103810854318443432] |