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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 40 |
| 4 | 1126 |
| 5 | 92440 |
| 6 | 22559276 |
| 7 | 16468584194 |
| 8 | 36033333480881 |
| 9 | 236450784546518006 |
| 10 | 4654297351684653345788 |
| 11 | 274836259327539399144691019 |
| 12 | 48686693681325683653963188907344 |
| 13 | 25874153864215746591981599665978198380 |
[1,1,4,40,1126,92440,22559276,16468584194, 36033333480881,236450784546518006, 4654297351684653345788, 274836259327539399144691019, 48686693681325683653963188907344, 25874153864215746591981599665978198380] |