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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 23 |
| 5 | 62 |
| 6 | 263 |
| 7 | 815 |
| 8 | 3641 |
| 9 | 12300 |
| 10 | 56667 |
| 11 | 202971 |
| 12 | 954066 |
| 13 | 3564277 |
| 14 | 16985607 |
| 15 | 65498160 |
| 16 | 315209452 |
| 17 | 1245818035 |
| 18 | 6039009631 |
| 19 | 24343527621 |
| 20 | 118650810900 |
| 21 | 486056238279 |
| 22 | 2379084219687 |
| 23 | 9877543772753 |
| 24 | 48508370650463 |
| 25 | 203692718352749 |
| 26 | 1002991082498646 |
| 27 | 4252712706392436 |
| 28 | 20985613117596447 |
[1,1,3,6,23,62,263,815,3641,12300,56667,202971, 954066,3564277,16985607,65498160,315209452, 1245818035,6039009631,24343527621,118650810900, 486056238279,2379084219687,9877543772753, 48508370650463,203692718352749,1002991082498646, 4252712706392436,20985613117596447] |