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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 20 |
| 5 | 115 |
| 6 | 714 |
| 7 | 5033 |
| 8 | 40312 |
| 9 | 362871 |
| 10 | 3628790 |
| 11 | 39916789 |
| 12 | 479001588 |
| 13 | 6227020787 |
| 14 | 87178291186 |
| 15 | 1307674367985 |
| 16 | 20922789887984 |
| 17 | 355687428095983 |
| 18 | 6402373705727982 |
| 19 | 121645100408831981 |
| 20 | 2432902008176639980 |
| 21 | 51090942171709439979 |
| 22 | 1124000727777607679978 |
[1,0,0,3,20,115,714,5033,40312,362871,3628790, 39916789,479001588,6227020787,87178291186, 1307674367985,20922789887984,355687428095983, 6402373705727982,121645100408831981, 2432902008176639980,51090942171709439979, 1124000727777607679978] |