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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 24 |
| 5 | 60 |
| 6 | 247 |
| 7 | 725 |
| 8 | 3142 |
| 9 | 9976 |
| 10 | 44566 |
| 11 | 150364 |
| 12 | 683268 |
| 13 | 2409852 |
| 14 | 11098347 |
| 15 | 40453800 |
| 16 | 188206351 |
| 17 | 704307402 |
| 18 | 3302109484 |
| 19 | 12625419479 |
| 20 | 59563688027 |
| 21 | 231816392010 |
| 22 | 1099281724137 |
| 23 | 4342743536033 |
| 24 | 20681409598268 |
| 25 | 82754124982121 |
| 26 | 395518720240174 |
| 27 | 1600228685069442 |
| 28 | 7671788362735186 |
[1,1,3,6,24,60,247,725,3142,9976,44566,150364, 683268,2409852,11098347,40453800,188206351, 704307402,3302109484,12625419479,59563688027, 231816392010,1099281724137,4342743536033, 20681409598268,82754124982121,395518720240174, 1600228685069442,7671788362735186] |