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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 70 |
| 9 | 1260 |
| 10 | 13650 |
| 11 | 115500 |
| 12 | 841995 |
| 13 | 5555550 |
| 14 | 34139105 |
| 15 | 198948750 |
| 16 | 1175994820 |
| 17 | 10315705400 |
| 18 | 192609389700 |
| 19 | 4563951046200 |
| 20 | 98992258506345 |
| 21 | 1898260633492650 |
| 22 | 32787422848455275 |
| 23 | 520556451785466250 |
| 24 | 7722233521138092726 |
| 25 | 108688302800107222500 |
[1,0,0,0,0,0,0,0,70,1260,13650,115500,841995, 5555550,34139105,198948750,1175994820,10315705400, 192609389700,4563951046200,98992258506345, 1898260633492650,32787422848455275, 520556451785466250,7722233521138092726, 108688302800107222500] |