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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 19 |
| 3 | 68 |
| 4 | 240 |
| 5 | 847 |
| 6 | 3003 |
| 7 | 10712 |
| 8 | 38454 |
| 9 | 138890 |
| 10 | 504526 |
| 11 | 1842392 |
| 12 | 6760390 |
| 13 | 24915555 |
| 14 | 92196075 |
| 15 | 342411120 |
| 16 | 1275977670 |
| 17 | 4769563590 |
| 18 | 17879195130 |
| 19 | 67197912600 |
| 20 | 253172676120 |
| 21 | 955992790038 |
| 22 | 3617431679934 |
| 23 | 13714878284368 |
[1,5,19,68,240,847,3003,10712,38454,138890,504526, 1842392,6760390,24915555,92196075,342411120, 1275977670,4769563590,17879195130,67197912600, 253172676120,955992790038,3617431679934, 13714878284368] |