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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 3 |
| 3 | 7 |
| 4 | 20 |
| 5 | 67 |
| 6 | 255 |
| 7 | 1080 |
| 8 | 5017 |
| 9 | 25287 |
| 10 | 137122 |
| 11 | 794545 |
| 12 | 4892167 |
| 13 | 31858034 |
| 14 | 218543759 |
| 15 | 1573857867 |
| 16 | 11863100692 |
| 17 | 93345011951 |
| 18 | 764941675963 |
| 19 | 6514819011216 |
| 20 | 57556900440429 |
| 21 | 526593974392123 |
| 22 | 4981585554604074 |
| 23 | 48658721593531669 |
| 24 | 490110875149889635 |
[1,2,3,7,20,67,255,1080,5017,25287,137122,794545, 4892167,31858034,218543759,1573857867,11863100692, 93345011951,764941675963,6514819011216, 57556900440429,526593974392123,4981585554604074, 48658721593531669,490110875149889635] |