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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 11 |
| 3 | 62 |
| 4 | 395 |
| 5 | 2662 |
| 6 | 18720 |
| 7 | 135738 |
| 8 | 1007607 |
| 9 | 7619456 |
| 10 | 58488028 |
| 11 | 454556544 |
| 12 | 3569655975 |
| 13 | 28282204680 |
| 14 | 225796917864 |
| 15 | 1814732935968 |
| 16 | 14670580718486 |
| 17 | 119215212413412 |
| 18 | 973246346463636 |
| 19 | 7978384233270126 |
| 20 | 65649676250344747 |
| 21 | 542031604244083664 |
[1,2,11,62,395,2662,18720,135738,1007607,7619456, 58488028,454556544,3569655975,28282204680, 225796917864,1814732935968,14670580718486, 119215212413412,973246346463636,7978384233270126, 65649676250344747,542031604244083664] |