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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 38 |
| 7 | 220 |
| 8 | 1182 |
| 9 | 5244 |
| 10 | 21677 |
| 11 | 83121 |
| 12 | 317190 |
| 13 | 1238406 |
| 14 | 5171963 |
| 15 | 23008470 |
| 16 | 106902558 |
| 17 | 502056620 |
| 18 | 2337251474 |
| 19 | 10681338960 |
| 20 | 47951784552 |
| 21 | 212639292310 |
| 22 | 939284216977 |
| 23 | 4165475057853 |
| 24 | 18644903265192 |
| 25 | 84352282521820 |
[1,1,1,2,6,38,220,1182,5244,21677,83121,317190, 1238406,5171963,23008470,106902558,502056620, 2337251474,10681338960,47951784552,212639292310, 939284216977,4165475057853,18644903265192, 84352282521820] |