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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 2 |
| 3 | 8 |
| 4 | 16 |
| 5 | 48 |
| 6 | 136 |
| 7 | 384 |
| 8 | 1184 |
| 9 | 3520 |
| 10 | 10944 |
| 11 | 34048 |
| 12 | 107008 |
| 13 | 340480 |
| 14 | 1087104 |
| 15 | 3502080 |
| 16 | 11333120 |
| 17 | 36867072 |
| 18 | 120491008 |
| 19 | 395276288 |
| 20 | 1301700608 |
| 21 | 4300414976 |
| 22 | 14250496000 |
| 23 | 47353233408 |
| 24 | 157747462144 |
| 25 | 526740717568 |
| 26 | 1762653863936 |
| 27 | 5910312910848 |
[1,2,2,8,16,48,136,384,1184,3520,10944,34048, 107008,340480,1087104,3502080,11333120,36867072, 120491008,395276288,1301700608,4300414976, 14250496000,47353233408,157747462144,526740717568, 1762653863936,5910312910848] |