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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 22 |
| 6 | 73 |
| 7 | 246 |
| 8 | 844 |
| 9 | 2936 |
| 10 | 10334 |
| 11 | 36736 |
| 12 | 131709 |
| 13 | 475714 |
| 14 | 1729345 |
| 15 | 6322534 |
| 16 | 23232616 |
| 17 | 85757008 |
| 18 | 317839438 |
| 19 | 1182341740 |
| 20 | 4412949358 |
| 21 | 16521076012 |
| 22 | 62024023306 |
| 23 | 233451103612 |
| 24 | 880764587512 |
| 25 | 3330234867792 |
| 26 | 12617475113968 |
[0,1,2,7,22,73,246,844,2936,10334,36736,131709, 475714,1729345,6322534,23232616,85757008, 317839438,1182341740,4412949358,16521076012, 62024023306,233451103612,880764587512, 3330234867792,12617475113968] |