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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 54 |
| 5 | 955 |
| 6 | 11760 |
| 7 | 122941 |
| 8 | 1175034 |
| 9 | 10595215 |
| 10 | 91506420 |
| 11 | 763624081 |
| 12 | 6194818014 |
| 13 | 49084747075 |
| 14 | 381338401080 |
| 15 | 2914184784421 |
| 16 | 21965095364994 |
| 17 | 163656285828535 |
| 18 | 1207613518375740 |
| 19 | 8838842878371961 |
| 20 | 64253768864671974 |
| 21 | 464416229729871595 |
| 22 | 3340518964319750400 |
[0,0,0,1,54,955,11760,122941,1175034,10595215, 91506420,763624081,6194818014,49084747075, 381338401080,2914184784421,21965095364994, 163656285828535,1207613518375740,8838842878371961, 64253768864671974,464416229729871595, 3340518964319750400] |