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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 55 |
| 6 | 825 |
| 7 | 20818 |
| 8 | 925036 |
| 9 | 76321756 |
| 10 | 12143833740 |
| 11 | 3786364993664 |
| 12 | 2323363153263768 |
| 13 | 2810644049356050752 |
| 14 | 6714880790313869814368 |
| 15 | 31734660624638397560681792 |
| 16 | 297106568651256947892439231872 |
| 17 | 5516820501457062391874183605225216 |
| 18 | 203371936690880564729559424288326233856 |
| 19 | 14896201998273652941883043518617399703696384 |
[0,0,1,6,55,825,20818,925036,76321756,12143833740, 3786364993664,2323363153263768, 2810644049356050752,6714880790313869814368, 31734660624638397560681792, 297106568651256947892439231872, 5516820501457062391874183605225216, 203371936690880564729559424288326233856, 14896201998273652941883043518617399703696384] |