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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 24 |
| 5 | 84 |
| 6 | 335 |
| 7 | 1495 |
| 8 | 7381 |
| 9 | 39912 |
| 10 | 234360 |
| 11 | 1483864 |
| 12 | 10070570 |
| 13 | 72885794 |
| 14 | 560059512 |
| 15 | 4551397316 |
| 16 | 38984638708 |
| 17 | 350888140187 |
| 18 | 3309798388178 |
| 19 | 32639617094998 |
| 20 | 335781293403494 |
| 21 | 3596524434640951 |
| 22 | 40035909421823293 |
[1,1,3,8,24,84,335,1495,7381,39912,234360,1483864, 10070570,72885794,560059512,4551397316, 38984638708,350888140187,3309798388178, 32639617094998,335781293403494,3596524434640951, 40035909421823293] |