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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 69 |
| 5 | 233 |
| 6 | 1123 |
| 7 | 4193 |
| 8 | 20445 |
| 9 | 79657 |
| 10 | 391523 |
| 11 | 1581335 |
| 12 | 7802551 |
| 13 | 32250205 |
| 14 | 159611321 |
| 15 | 671656495 |
| 16 | 3331359929 |
| 17 | 14211713979 |
| 18 | 70601547625 |
| 19 | 304539943445 |
| 20 | 1514683890949 |
| 21 | 6593142774295 |
| 22 | 32821605294277 |
| 23 | 143954466315923 |
| 24 | 717132984141773 |
| 25 | 3165624935768595 |
| 26 | 15779028426737607 |
| 27 | 70039409190070017 |
[1,1,5,15,69,233,1123,4193,20445,79657,391523, 1581335,7802551,32250205,159611321,671656495, 3331359929,14211713979,70601547625,304539943445, 1514683890949,6593142774295,32821605294277, 143954466315923,717132984141773,3165624935768595, 15779028426737607,70039409190070017] |