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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 32 |
| 4 | 170 |
| 5 | 912 |
| 6 | 4942 |
| 7 | 27008 |
| 8 | 148626 |
| 9 | 822560 |
| 10 | 4573910 |
| 11 | 25534368 |
| 12 | 143027898 |
| 13 | 803467056 |
| 14 | 4524812190 |
| 15 | 25537728000 |
| 16 | 144411206178 |
| 17 | 818017823808 |
| 18 | 4640757865126 |
| 19 | 26364054632480 |
| 20 | 149959897539018 |
| 21 | 853941394691792 |
| 22 | 4867745532495086 |
| 23 | 27773897706129792 |
[0,1,6,32,170,912,4942,27008,148626,822560, 4573910,25534368,143027898,803467056,4524812190, 25537728000,144411206178,818017823808, 4640757865126,26364054632480,149959897539018, 853941394691792,4867745532495086, 27773897706129792] |