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| n | a(n) |
|---|---|
| 1 | 456 |
| 2 | 3270 |
| 3 | 23136 |
| 4 | 164004 |
| 5 | 1160616 |
| 6 | 8216484 |
| 7 | 58154912 |
| 8 | 411637168 |
| 9 | 2913595712 |
| 10 | 20622837480 |
| 11 | 145970677056 |
| 12 | 1033197881712 |
| 13 | 7313093248992 |
| 14 | 51762926098992 |
| 15 | 366383987227392 |
| 16 | 2593308396911680 |
| 17 | 18355737644921600 |
| 18 | 129924040926296800 |
[456,3270,23136,164004,1160616,8216484,58154912, 411637168,2913595712,20622837480,145970677056, 1033197881712,7313093248992,51762926098992, 366383987227392,2593308396911680, 18355737644921600,129924040926296800] |