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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 67 |
| 5 | 424 |
| 6 | 3093 |
| 7 | 26060 |
| 8 | 233917 |
| 9 | 2427224 |
| 10 | 27565317 |
| 11 | 339002146 |
| 12 | 4450167269 |
| 13 | 63343680802 |
| 14 | 964189902141 |
| 15 | 15769859929260 |
| 16 | 270255218753593 |
| 17 | 4913097747513800 |
| 18 | 94513145955643993 |
| 19 | 1904990351069631390 |
| 20 | 40153307898034641361 |
| 21 | 893402292594225679438 |
[1,1,3,14,67,424,3093,26060,233917,2427224, 27565317,339002146,4450167269,63343680802, 964189902141,15769859929260,270255218753593, 4913097747513800,94513145955643993, 1904990351069631390,40153307898034641361, 893402292594225679438] |