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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | 2 |
| 5 | 2 |
| 6 | 10 |
| 7 | 28 |
| 8 | 130 |
| 9 | 564 |
| 10 | 3102 |
| 11 | 17464 |
| 12 | 114282 |
| 13 | 784008 |
| 14 | 5987482 |
| 15 | 48279164 |
| 16 | 422742854 |
| 17 | 3909897740 |
| 18 | 38675519334 |
| 19 | 403121938616 |
| 20 | 4449327971330 |
| 21 | 51570742407808 |
| 22 | 628575203791026 |
| 23 | 8017017724008788 |
| 24 | 106974723312803902 |
| 25 | 1488628872502049348 |
[1,1,0,2,2,10,28,130,564,3102,17464,114282,784008, 5987482,48279164,422742854,3909897740,38675519334, 403121938616,4449327971330,51570742407808, 628575203791026,8017017724008788, 106974723312803902,1488628872502049348] |