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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 15 |
| 3 | 344 |
| 4 | 6835 |
| 5 | 119392 |
| 6 | 2136080 |
| 7 | 38329669 |
| 8 | 688355077 |
| 9 | 12374676591 |
| 10 | 222673114420 |
| 11 | 4005005917279 |
| 12 | 72004800735036 |
| 13 | 1294444641691072 |
| 14 | 23273376392535695 |
| 15 | 418470613768822683 |
| 16 | 7524342117053834729 |
| 17 | 135288703461639048592 |
| 18 | 2432489164334993344213 |
[1,1,15,344,6835,119392,2136080,38329669, 688355077,12374676591,222673114420,4005005917279, 72004800735036,1294444641691072,23273376392535695, 418470613768822683,7524342117053834729, 135288703461639048592,2432489164334993344213] |