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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 56 |
| 6 | 1031 |
| 7 | 27189 |
| 8 | 1165424 |
| 9 | 89723096 |
| 10 | 13371146135 |
| 11 | 3989665389689 |
| 12 | 2388718032951812 |
| 13 | 2852540291841718752 |
| 14 | 6768426738881535155247 |
| 15 | 31870401029679493862010949 |
| 16 | 297787425565749788134314214272 |
[1,1,1,1,4,56,1031,27189,1165424,89723096, 13371146135,3989665389689,2388718032951812, 2852540291841718752,6768426738881535155247, 31870401029679493862010949, 297787425565749788134314214272] |