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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 20 |
| 3 | 80 |
| 4 | 320 |
| 5 | 1280 |
| 6 | 5120 |
| 7 | 20470 |
| 8 | 81840 |
| 9 | 327210 |
| 10 | 1308240 |
| 11 | 5230560 |
| 12 | 20912640 |
| 13 | 83612160 |
| 14 | 334295130 |
| 15 | 1336566780 |
| 16 | 5343813270 |
| 17 | 21365442180 |
| 18 | 85422543120 |
| 19 | 341533342080 |
| 20 | 1365506334720 |
| 21 | 5459518355670 |
| 22 | 21828050092440 |
| 23 | 87272125451010 |
[1,5,20,80,320,1280,5120,20470,81840,327210, 1308240,5230560,20912640,83612160,334295130, 1336566780,5343813270,21365442180,85422543120, 341533342080,1365506334720,5459518355670, 21828050092440,87272125451010] |