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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 2 |
| 6 | 28 |
| 7 | 252 |
| 8 | 1890 |
| 9 | 13020 |
| 10 | 86564 |
| 11 | 571944 |
| 12 | 3826230 |
| 13 | 26233662 |
| 14 | 185746860 |
| 15 | 1364083084 |
| 16 | 10410773076 |
| 17 | 82609104802 |
| 18 | 681130756224 |
| 19 | 5829231836494 |
| 20 | 51711093240518 |
| 21 | 474821049202852 |
| 22 | 4506533206814480 |
| 23 | 44151320870760216 |
| 24 | 445956292457725714 |
[0,0,0,0,0,2,28,252,1890,13020,86564,571944, 3826230,26233662,185746860,1364083084,10410773076, 82609104802,681130756224,5829231836494, 51711093240518,474821049202852,4506533206814480, 44151320870760216,445956292457725714] |