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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 18 |
| 7 | 50 |
| 8 | 133 |
| 9 | 349 |
| 10 | 919 |
| 11 | 2443 |
| 12 | 6559 |
| 13 | 17759 |
| 14 | 48417 |
| 15 | 132765 |
| 16 | 365883 |
| 17 | 1012827 |
| 18 | 2814975 |
| 19 | 7852359 |
| 20 | 21977172 |
| 21 | 61697208 |
| 22 | 173688720 |
| 23 | 490222392 |
| 24 | 1386896799 |
| 25 | 3932313671 |
| 26 | 11172152779 |
| 27 | 31801604227 |
| 28 | 90683754826 |
| 29 | 259017103918 |
[1,1,1,1,2,6,18,50,133,349,919,2443,6559,17759, 48417,132765,365883,1012827,2814975,7852359, 21977172,61697208,173688720,490222392,1386896799, 3932313671,11172152779,31801604227,90683754826, 259017103918] |