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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 10 |
| 5 | 76 |
| 6 | 530 |
| 7 | 3701 |
| 8 | 27810 |
| 9 | 237151 |
| 10 | 2316350 |
| 11 | 25135126 |
| 12 | 292106400 |
| 13 | 3559029501 |
| 14 | 45211131460 |
| 15 | 600619791201 |
| 16 | 8384107777030 |
| 17 | 123237338584576 |
| 18 | 1904128564485610 |
| 19 | 30789744821412401 |
| 20 | 518479182191232950 |
| 21 | 9057086806410632751 |
| 22 | 163745788914416588050 |
[0,1,0,1,10,76,530,3701,27810,237151,2316350, 25135126,292106400,3559029501,45211131460, 600619791201,8384107777030,123237338584576, 1904128564485610,30789744821412401, 518479182191232950,9057086806410632751, 163745788914416588050] |