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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 39 |
| 4 | 308 |
| 5 | 3013 |
| 6 | 33300 |
| 7 | 394340 |
| 8 | 4878109 |
| 9 | 62232321 |
| 10 | 812825244 |
| 11 | 10818489817 |
| 12 | 146250545528 |
| 13 | 2003199281223 |
| 14 | 27747288947266 |
| 15 | 388087900316025 |
| 16 | 5474206895126243 |
| 17 | 77795972452841542 |
| 18 | 1112947041203866164 |
| 19 | 16016508647052018408 |
| 20 | 231727628211887783830 |
| 21 | 3368855109532696440867 |
[1,2,7,39,308,3013,33300,394340,4878109,62232321, 812825244,10818489817,146250545528,2003199281223, 27747288947266,388087900316025,5474206895126243, 77795972452841542,1112947041203866164, 16016508647052018408,231727628211887783830, 3368855109532696440867] |