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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 4 |
| 5 | 84 |
| 6 | 296 |
| 7 | 2680 |
| 8 | 19776 |
| 9 | 182336 |
| 10 | 1812352 |
| 11 | 19963008 |
| 12 | 239490560 |
| 13 | 3113532928 |
| 14 | 43589096448 |
| 15 | 653837290496 |
| 16 | 10461394714624 |
| 17 | 177843714539520 |
| 18 | 3201186851815424 |
| 19 | 60822550206644224 |
| 20 | 1216451004083601408 |
| 21 | 25545471085864681472 |
| 22 | 562000363888782868480 |
| 23 | 12926008369442532360192 |
| 24 | 310224200866619627405312 |
| 25 | 7755605021665493184937984 |
[1,0,1,5,4,84,296,2680,19776,182336,1812352, 19963008,239490560,3113532928,43589096448, 653837290496,10461394714624,177843714539520, 3201186851815424,60822550206644224, 1216451004083601408,25545471085864681472, 562000363888782868480,12926008369442532360192, 310224200866619627405312, 7755605021665493184937984] |