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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 10 |
| 4 | 40 |
| 5 | 260 |
| 6 | 1240 |
| 7 | 6510 |
| 8 | 32240 |
| 9 | 162760 |
| 10 | 812240 |
| 11 | 4069010 |
| 12 | 20337240 |
| 13 | 101725260 |
| 14 | 508587240 |
| 15 | 2543131510 |
| 16 | 12715462240 |
| 17 | 63578287760 |
| 18 | 317890462240 |
| 19 | 1589457194010 |
| 20 | 7947281087240 |
| 21 | 39736429850260 |
[0,0,0,10,40,260,1240,6510,32240,162760,812240, 4069010,20337240,101725260,508587240,2543131510, 12715462240,63578287760,317890462240, 1589457194010,7947281087240,39736429850260] |