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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 72 |
| 4 | 664 |
| 5 | 7440 |
| 6 | 97712 |
| 7 | 1468768 |
| 8 | 24825184 |
| 9 | 465516672 |
| 10 | 9582002688 |
| 11 | 214642099584 |
| 12 | 5195322070656 |
| 13 | 135064965744384 |
| 14 | 3752151488840448 |
| 15 | 110892824334154752 |
| 16 | 3473236656134243328 |
| 17 | 114893633354895538176 |
| 18 | 4002000861023966189568 |
| 19 | 146388324613230926979072 |
[1,2,10,72,664,7440,97712,1468768,24825184, 465516672,9582002688,214642099584,5195322070656, 135064965744384,3752151488840448, 110892824334154752,3473236656134243328, 114893633354895538176,4002000861023966189568, 146388324613230926979072] |