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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 16 |
| 6 | 96 |
| 7 | 812 |
| 8 | 10957 |
| 9 | 260494 |
| 10 | 11713772 |
| 11 | 1006689871 |
| 12 | 164059928509 |
| 13 | 50335918374222 |
| 14 | 29003488479015273 |
| 15 | 31397381309486933777 |
| 16 | 63969560164056545231089 |
| 17 | 245871831711240782887877980 |
| 18 | 1787331725280384281389706209909 |
| 19 | 24636021429463931875328533035140871 |
| 20 | 645465483198968863672173418327800803328 |
[1,0,0,1,3,16,96,812,10957,260494,11713772, 1006689871,164059928509,50335918374222, 29003488479015273,31397381309486933777, 63969560164056545231089, 245871831711240782887877980, 1787331725280384281389706209909, 24636021429463931875328533035140871, 645465483198968863672173418327800803328] |