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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 5 |
| 5 | 25 |
| 6 | 269 |
| 7 | 1883 |
| 8 | 20103 |
| 9 | 180927 |
| 10 | 2172149 |
| 11 | 23893639 |
| 12 | 326640467 |
| 13 | 4246326071 |
| 14 | 65675585793 |
| 15 | 985133786895 |
| 16 | 17069814958319 |
| 17 | 290186854291423 |
| 18 | 5579050805341613 |
| 19 | 106001965301490647 |
| 20 | 2241684406438644939 |
| 21 | 47075372535211543719 |
[0,0,0,0,5,25,269,1883,20103,180927,2172149, 23893639,326640467,4246326071,65675585793, 985133786895,17069814958319,290186854291423, 5579050805341613,106001965301490647, 2241684406438644939,47075372535211543719] |