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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 5 |
| 3 | 6 |
| 4 | 35 |
| 5 | 80 |
| 6 | 306 |
| 7 | 880 |
| 8 | 3003 |
| 9 | 9384 |
| 10 | 31070 |
| 11 | 100226 |
| 12 | 330015 |
| 13 | 1079392 |
| 14 | 3559001 |
| 15 | 11724930 |
| 16 | 38772445 |
| 17 | 128313480 |
| 18 | 425553513 |
| 19 | 1412911148 |
| 20 | 4697992880 |
| 21 | 15637660896 |
| 22 | 52109660575 |
| 23 | 173809285676 |
| 24 | 580261793715 |
| 25 | 1938778221800 |
| 26 | 6482844907190 |
| 27 | 21692435752290 |
| 28 | 72633495206803 |
[1,0,5,6,35,80,306,880,3003,9384,31070,100226, 330015,1079392,3559001,11724930,38772445, 128313480,425553513,1412911148,4697992880, 15637660896,52109660575,173809285676,580261793715, 1938778221800,6482844907190,21692435752290, 72633495206803] |