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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 10 |
| 5 | 99 |
| 6 | 1146 |
| 7 | 15422 |
| 8 | 237135 |
| 9 | 4106680 |
| 10 | 79154927 |
| 11 | 1681383864 |
| 12 | 39034539488 |
| 13 | 983466451011 |
| 14 | 26728184505750 |
| 15 | 779476074425297 |
| 16 | 24281301468714902 |
| 17 | 804688068731837874 |
| 18 | 28269541494090294129 |
| 19 | 1049450257149017422000 |
| 20 | 41050171013933837206545 |
[1,0,0,1,10,99,1146,15422,237135,4106680,79154927, 1681383864,39034539488,983466451011, 26728184505750,779476074425297,24281301468714902, 804688068731837874,28269541494090294129, 1049450257149017422000,41050171013933837206545] |