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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 203 |
| 7 | 877 |
| 8 | 4140 |
| 9 | 21147 |
| 10 | 115974 |
| 11 | 678434 |
| 12 | 4209827 |
| 13 | 27578206 |
| 14 | 189954361 |
| 15 | 1370870811 |
| 16 | 10334533723 |
| 17 | 81166980407 |
| 18 | 662588540048 |
| 19 | 5610196619724 |
| 20 | 49177794178940 |
| 21 | 445536788068643 |
| 22 | 4165402700226511 |
| 23 | 40131393651398259 |
| 24 | 397935154986242021 |
[1,1,2,5,15,52,203,877,4140,21147,115974,678434, 4209827,27578206,189954361,1370870811,10334533723, 81166980407,662588540048,5610196619724, 49177794178940,445536788068643,4165402700226511, 40131393651398259,397935154986242021] |