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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 44 |
| 6 | 176 |
| 7 | 788 |
| 8 | 3936 |
| 9 | 23264 |
| 10 | 152112 |
| 11 | 1104876 |
| 12 | 8725320 |
| 13 | 74715908 |
| 14 | 687915040 |
| 15 | 6782261964 |
| 16 | 71294227456 |
| 17 | 796138700016 |
| 18 | 9409401651840 |
| 19 | 117378774461812 |
[1,2,4,12,44,176,788,3936,23264,152112,1104876, 8725320,74715908,687915040,6782261964,71294227456, 796138700016,9409401651840,117378774461812] |