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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 11 |
| 4 | 100 |
| 5 | 1270 |
| 6 | 20720 |
| 7 | 413000 |
| 8 | 9726640 |
| 9 | 264279400 |
| 10 | 8137329200 |
| 11 | 280012733000 |
| 12 | 10649265827200 |
| 13 | 443563134414400 |
| 14 | 20081317352096000 |
| 15 | 981847343837360000 |
| 16 | 51561200079861472000 |
| 17 | 2894410559695262608000 |
| 18 | 172959683650895741600000 |
| 19 | 10961750255473947129200000 |
[0,1,2,11,100,1270,20720,413000,9726640,264279400, 8137329200,280012733000,10649265827200, 443563134414400,20081317352096000, 981847343837360000,51561200079861472000, 2894410559695262608000,172959683650895741600000, 10961750255473947129200000] |