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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 117 |
| 5 | 498 |
| 6 | 2139 |
| 7 | 9232 |
| 8 | 39953 |
| 9 | 173162 |
| 10 | 751103 |
| 11 | 3259132 |
| 12 | 14142973 |
| 13 | 61367542 |
| 14 | 266223083 |
| 15 | 1154592752 |
| 16 | 5005724185 |
| 17 | 21694354406 |
| 18 | 93985418399 |
| 19 | 407009142836 |
| 20 | 1761880487509 |
| 21 | 7623911365210 |
| 22 | 32976925264827 |
| 23 | 142585750821408 |
| 24 | 616281411472257 |
| 25 | 2662702949358158 |
[1,2,7,28,117,498,2139,9232,39953,173162,751103, 3259132,14142973,61367542,266223083,1154592752, 5005724185,21694354406,93985418399,407009142836, 1761880487509,7623911365210,32976925264827, 142585750821408,616281411472257,2662702949358158] |