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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 4 |
| 5 | 65 |
| 6 | 1026 |
| 7 | 17857 |
| 8 | 349224 |
| 9 | 7657281 |
| 10 | 186895270 |
| 11 | 5037424601 |
| 12 | 148805552556 |
| 13 | 4784793219505 |
| 14 | 166458635341194 |
| 15 | 6231891513395745 |
| 16 | 249886992888096976 |
| 17 | 10686839817678846209 |
| 18 | 485632267141865950926 |
| 19 | 23370062118676064101801 |
| 20 | 1187393725239246382405140 |
[0,0,0,4,65,1026,17857,349224,7657281,186895270, 5037424601,148805552556,4784793219505, 166458635341194,6231891513395745, 249886992888096976,10686839817678846209, 485632267141865950926,23370062118676064101801, 1187393725239246382405140] |