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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 60 |
| 4 | 398 |
| 5 | 2820 |
| 6 | 20892 |
| 7 | 159868 |
| 8 | 1253758 |
| 9 | 10024070 |
| 10 | 81400672 |
| 11 | 669532924 |
| 12 | 5566386324 |
| 13 | 46701736772 |
| 14 | 394910202608 |
| 15 | 3362210548344 |
| 16 | 28797181196766 |
| 17 | 247955463799812 |
| 18 | 2145088563952510 |
| 19 | 18636002388075260 |
| 20 | 162523319555310664 |
| 21 | 1422259430668179592 |
| 22 | 12485554521209720492 |
| 23 | 109922263517662775292 |
[1,2,10,60,398,2820,20892,159868,1253758,10024070, 81400672,669532924,5566386324,46701736772, 394910202608,3362210548344,28797181196766, 247955463799812,2145088563952510, 18636002388075260,162523319555310664, 1422259430668179592,12485554521209720492, 109922263517662775292] |