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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 10 |
| 4 | 70 |
| 5 | 431 |
| 6 | 2534 |
| 7 | 14820 |
| 8 | 88267 |
| 9 | 542912 |
| 10 | 3475978 |
| 11 | 23253693 |
| 12 | 162723444 |
| 13 | 1190464900 |
| 14 | 9092400633 |
| 15 | 72370378750 |
| 16 | 599168889634 |
| 17 | 5150536258735 |
| 18 | 45891028609826 |
| 19 | 423144495659912 |
| 20 | 4031842435506171 |
| 21 | 39645279656283820 |
| 22 | 401806832058661334 |
| 23 | 4192631368792015237 |
| 24 | 44992655908959220440 |
[0,0,1,10,70,431,2534,14820,88267,542912,3475978, 23253693,162723444,1190464900,9092400633, 72370378750,599168889634,5150536258735, 45891028609826,423144495659912,4031842435506171, 39645279656283820,401806832058661334, 4192631368792015237,44992655908959220440] |