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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 203 |
| 7 | 877 |
| 8 | 4140 |
| 9 | 21147 |
| 10 | 115975 |
| 11 | 678570 |
| 12 | 4213597 |
| 13 | 27644436 |
| 14 | 190899230 |
| 15 | 1382953889 |
| 16 | 10479970386 |
| 17 | 82859701769 |
| 18 | 681942165393 |
| 19 | 5829591731684 |
| 20 | 51656311613107 |
| 21 | 473501669531146 |
| 22 | 4480550589850064 |
| 23 | 43672799989835155 |
[1,2,5,15,52,203,877,4140,21147,115975,678570, 4213597,27644436,190899230,1382953889,10479970386, 82859701769,681942165393,5829591731684, 51656311613107,473501669531146,4480550589850064, 43672799989835155] |