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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 22 |
| 5 | 115 |
| 6 | 761 |
| 7 | 5880 |
| 8 | 49897 |
| 9 | 460045 |
| 10 | 4621366 |
| 11 | 50385555 |
| 12 | 590795217 |
| 13 | 7389964400 |
| 14 | 98105330961 |
| 15 | 1377426850805 |
| 16 | 20388005470582 |
| 17 | 317112889169555 |
| 18 | 5167636268318921 |
| 19 | 88001180739368680 |
| 20 | 1562559584723343417 |
| 21 | 28871671817796197885 |
| 22 | 554116841783123679446 |
[1,0,1,5,22,115,761,5880,49897,460045,4621366, 50385555,590795217,7389964400,98105330961, 1377426850805,20388005470582,317112889169555, 5167636268318921,88001180739368680, 1562559584723343417,28871671817796197885, 554116841783123679446] |