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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 21 |
| 3 | 444 |
| 4 | 14415 |
| 5 | 637268 |
| 6 | 35822203 |
| 7 | 2450234160 |
| 8 | 197807272289 |
| 9 | 18431380399184 |
| 10 | 1948783220129813 |
| 11 | 230702141895062720 |
| 12 | 30251527782113610991 |
| 13 | 4355262112839582661824 |
| 14 | 683368350046603022039867 |
| 15 | 116136704024677305164141056 |
[1,2,21,444,14415,637268,35822203,2450234160, 197807272289,18431380399184,1948783220129813, 230702141895062720,30251527782113610991, 4355262112839582661824,683368350046603022039867, 116136704024677305164141056] |