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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 2 |
| 5 | 2 |
| 6 | 42 |
| 7 | 142 |
| 8 | 366 |
| 9 | 3082 |
| 10 | 18626 |
| 11 | 86990 |
| 12 | 596158 |
| 13 | 4485626 |
| 14 | 30214498 |
| 15 | 224897662 |
| 16 | 1871664190 |
| 17 | 15587540042 |
| 18 | 134045407458 |
| 19 | 1231183979886 |
| 20 | 11725017784574 |
| 21 | 114812031304986 |
| 22 | 1170100796863202 |
| 23 | 12371771640238174 |
| 24 | 134796972965052350 |
| 25 | 1514854948728869354 |
[1,0,0,2,2,2,42,142,366,3082,18626,86990,596158, 4485626,30214498,224897662,1871664190,15587540042, 134045407458,1231183979886,11725017784574, 114812031304986,1170100796863202, 12371771640238174,134796972965052350, 1514854948728869354] |