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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 1 |
| 5 | 20 |
| 6 | 1 |
| 7 | 420 |
| 8 | 1841 |
| 9 | 7140 |
| 10 | 190001 |
| 11 | 555940 |
| 12 | 12774881 |
| 13 | 141201060 |
| 14 | 946212001 |
| 15 | 25228809060 |
| 16 | 202847031121 |
| 17 | 3740829095780 |
| 18 | 66881800434001 |
| 19 | 733452394335780 |
| 20 | 19147386646802561 |
| 21 | 273971147946411300 |
| 22 | 5322649952666824001 |
| 23 | 124410236296546608100 |
| 24 | 2010649742531247641201 |
| 25 | 53865539929721514523620 |
| 26 | 1113617365649653498950001 |
[1,0,1,0,1,20,1,420,1841,7140,190001,555940, 12774881,141201060,946212001,25228809060, 202847031121,3740829095780,66881800434001, 733452394335780,19147386646802561, 273971147946411300,5322649952666824001, 124410236296546608100,2010649742531247641201, 53865539929721514523620,1113617365649653498950001] |