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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 21 |
| 3 | 237 |
| 4 | 3738 |
| 5 | 76212 |
| 6 | 1912350 |
| 7 | 57099816 |
| 8 | 1979628552 |
| 9 | 78224586240 |
| 10 | 3472089084072 |
| 11 | 171098204829120 |
| 12 | 9271248509444544 |
| 13 | 548011290335056272 |
| 14 | 35095593433694127696 |
| 15 | 2421035179995679335360 |
| 16 | 178997036386314294247680 |
| 17 | 14121215676864610247122560 |
[1,3,21,237,3738,76212,1912350,57099816, 1979628552,78224586240,3472089084072, 171098204829120,9271248509444544, 548011290335056272,35095593433694127696, 2421035179995679335360,178997036386314294247680, 14121215676864610247122560] |