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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 | 21146 |
| 10 | 115965 |
| 11 | 678460 |
| 12 | 4212497 |
| 13 | 27633712 |
| 14 | 190795218 |
| 15 | 1381942530 |
| 16 | 10470109267 |
| 17 | 82764226404 |
| 18 | 681048663329 |
| 19 | 5822029128397 |
| 20 | 51610194855972 |
| 21 | 473631475252041 |
| 22 | 4492967510009533 |
| 23 | 43996047374513046 |
| 24 | 444151309687221889 |
| 25 | 4617189912288741028 |
[1,1,2,5,15,52,203,877,4140,21146,115965,678460, 4212497,27633712,190795218,1381942530,10470109267, 82764226404,681048663329,5822029128397, 51610194855972,473631475252041,4492967510009533, 43996047374513046,444151309687221889, 4617189912288741028] |