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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 62 |
| 5 | 312 |
| 6 | 1873 |
| 7 | 13117 |
| 8 | 104937 |
| 9 | 944441 |
| 10 | 9444416 |
| 11 | 103888585 |
| 12 | 1246663020 |
| 13 | 16206619263 |
| 14 | 226892669691 |
| 15 | 3403390045367 |
| 16 | 54454240725881 |
| 17 | 925722092339993 |
| 18 | 16662997662119888 |
| 19 | 316596955580277878 |
| 20 | 6331939111605557573 |
[2,5,15,62,312,1873,13117,104937,944441,9444416, 103888585,1246663020,16206619263,226892669691, 3403390045367,54454240725881,925722092339993, 16662997662119888,316596955580277878, 6331939111605557573] |