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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 25 |
| 6 | 102 |
| 7 | 455 |
| 8 | 2192 |
| 9 | 11203 |
| 10 | 59814 |
| 11 | 329343 |
| 12 | 1851911 |
| 13 | 10560334 |
| 14 | 60776590 |
| 15 | 351887190 |
| 16 | 2045329031 |
| 17 | 11918417465 |
| 18 | 69563676328 |
| 19 | 406447507101 |
| 20 | 2376416054328 |
| 21 | 13900548090293 |
| 22 | 81332697848104 |
| 23 | 475968841105687 |
| 24 | 2785759950405621 |
[0,1,2,7,25,102,455,2192,11203,59814,329343, 1851911,10560334,60776590,351887190,2045329031, 11918417465,69563676328,406447507101, 2376416054328,13900548090293,81332697848104, 475968841105687,2785759950405621] |