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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 36 |
| 5 | 120 |
| 6 | 451 |
| 7 | 1626 |
| 8 | 6426 |
| 9 | 24185 |
| 10 | 98084 |
| 11 | 381500 |
| 12 | 1568582 |
| 13 | 6253145 |
| 14 | 25945355 |
| 15 | 105297818 |
| 16 | 440103945 |
| 17 | 1809396632 |
| 18 | 7609736345 |
| 19 | 31591826888 |
| 20 | 133555292794 |
| 21 | 558736339296 |
| 22 | 2372175262534 |
| 23 | 9986627300516 |
| 24 | 42550513983270 |
| 25 | 180067731713734 |
| 26 | 769559478434464 |
| 27 | 3270867038266924 |
| 28 | 14015828521820036 |
[1,1,4,10,36,120,451,1626,6426,24185,98084,381500, 1568582,6253145,25945355,105297818,440103945, 1809396632,7609736345,31591826888,133555292794, 558736339296,2372175262534,9986627300516, 42550513983270,180067731713734,769559478434464, 3270867038266924,14015828521820036] |