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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 24 |
| 3 | 504 |
| 4 | 3672 |
| 5 | 16272 |
| 6 | 53784 |
| 7 | 146184 |
| 8 | 345240 |
| 9 | 733344 |
| 10 | 1433880 |
| 11 | 2623128 |
| 12 | 4543704 |
| 13 | 7519536 |
| 14 | 11972376 |
| 15 | 18439848 |
| 16 | 27595032 |
| 17 | 40267584 |
| 18 | 57466392 |
| 19 | 80403768 |
| 20 | 110521176 |
| 21 | 149516496 |
| 22 | 199372824 |
| 23 | 262388808 |
| 24 | 341210520 |
| 25 | 438864864 |
| 26 | 558794520 |
| 27 | 704894424 |
[0,24,504,3672,16272,53784,146184,345240,733344, 1433880,2623128,4543704,7519536,11972376,18439848, 27595032,40267584,57466392,80403768,110521176, 149516496,199372824,262388808,341210520,438864864, 558794520,704894424] |