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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 12 |
| 3 | 58 |
| 4 | 256 |
| 5 | 1072 |
| 6 | 4336 |
| 7 | 17112 |
| 8 | 66304 |
| 9 | 253280 |
| 10 | 956608 |
| 11 | 3579680 |
| 12 | 13292544 |
| 13 | 49039360 |
| 14 | 179912448 |
| 15 | 656874368 |
| 16 | 2388205568 |
| 17 | 8650598912 |
| 18 | 31231020032 |
| 19 | 112419973632 |
| 20 | 403596148736 |
| 21 | 1445463642112 |
| 22 | 5165581660160 |
| 23 | 18423238924288 |
[0,2,12,58,256,1072,4336,17112,66304,253280, 956608,3579680,13292544,49039360,179912448, 656874368,2388205568,8650598912,31231020032, 112419973632,403596148736,1445463642112, 5165581660160,18423238924288] |