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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 82 |
| 5 | 495 |
| 6 | 3147 |
| 7 | 20812 |
| 8 | 141621 |
| 9 | 985287 |
| 10 | 6976369 |
| 11 | 50108232 |
| 12 | 364202415 |
| 13 | 2673756449 |
| 14 | 19797659586 |
| 15 | 147677816532 |
| 16 | 1108711280376 |
| 17 | 8371222635096 |
| 18 | 63525564996093 |
| 19 | 484243596619753 |
| 20 | 3706268752629237 |
| 21 | 28470703720193010 |
| 22 | 219432896755734137 |
[1,1,3,15,82,495,3147,20812,141621,985287,6976369, 50108232,364202415,2673756449,19797659586, 147677816532,1108711280376,8371222635096, 63525564996093,484243596619753,3706268752629237, 28470703720193010,219432896755734137] |