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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 2 |
| 3 | 12 |
| 4 | 22 |
| 5 | 144 |
| 6 | 318 |
| 7 | 2102 |
| 8 | 5120 |
| 9 | 34274 |
| 10 | 88352 |
| 11 | 597002 |
| 12 | 1599676 |
| 13 | 10879502 |
| 14 | 29983958 |
| 15 | 204851678 |
| 16 | 576914820 |
| 17 | 3953960052 |
| 18 | 11329537402 |
| 19 | 77815428652 |
| 20 | 226170428918 |
| 21 | 1555598157856 |
| 22 | 4576144621100 |
| 23 | 31500863667990 |
| 24 | 93634976287220 |
| 25 | 644808182456240 |
| 26 | 1934219875423410 |
[1,2,2,12,22,144,318,2102,5120,34274,88352,597002, 1599676,10879502,29983958,204851678,576914820, 3953960052,11329537402,77815428652,226170428918, 1555598157856,4576144621100,31500863667990, 93634976287220,644808182456240,1934219875423410] |