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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 5 |
| 5 | 9 |
| 6 | 52 |
| 7 | 130 |
| 8 | 855 |
| 9 | 2707 |
| 10 | 19921 |
| 11 | 75771 |
| 12 | 614866 |
| 13 | 2717570 |
| 14 | 24040451 |
| 15 | 120652827 |
| 16 | 1152972925 |
| 17 | 6460552857 |
| 18 | 66200911138 |
| 19 | 408845736040 |
| 20 | 4465023867757 |
| 21 | 30083964854141 |
| 22 | 348383154017581 |
| 23 | 2539795748336375 |
| 24 | 31052765897026352 |
| 25 | 243282175672281360 |
[1,0,1,1,5,9,52,130,855,2707,19921,75771,614866, 2717570,24040451,120652827,1152972925,6460552857, 66200911138,408845736040,4465023867757, 30083964854141,348383154017581,2539795748336375, 31052765897026352,243282175672281360] |