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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 50 |
| 4 | 392 |
| 5 | 2970 |
| 6 | 22022 |
| 7 | 160888 |
| 8 | 1162800 |
| 9 | 8335338 |
| 10 | 59366450 |
| 11 | 420630210 |
| 12 | 2967563040 |
| 13 | 20861295000 |
| 14 | 146203657992 |
| 15 | 1021964428880 |
| 16 | 7127260128736 |
| 17 | 49606676100234 |
| 18 | 344658278690250 |
| 19 | 2390849931605590 |
| 20 | 16561583202364200 |
| 21 | 114577083158683530 |
| 22 | 791757148201073670 |
[1,6,50,392,2970,22022,160888,1162800,8335338, 59366450,420630210,2967563040,20861295000, 146203657992,1021964428880,7127260128736, 49606676100234,344658278690250,2390849931605590, 16561583202364200,114577083158683530, 791757148201073670] |