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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 19 |
| 6 | 86 |
| 7 | 372 |
| 8 | 1825 |
| 9 | 9143 |
| 10 | 47801 |
| 11 | 254990 |
| 12 | 1391302 |
| 13 | 7713642 |
| 14 | 43401974 |
| 15 | 247216934 |
| 16 | 1423531255 |
| 17 | 8275108733 |
| 18 | 48511773461 |
| 19 | 286542497274 |
| 20 | 1704002332513 |
| 21 | 10195435737315 |
| 22 | 61341136938138 |
| 23 | 370933387552634 |
| 24 | 2253475545208390 |
| 25 | 13748639775492766 |
| 26 | 84211761819147696 |
[1,1,1,2,7,19,86,372,1825,9143,47801,254990, 1391302,7713642,43401974,247216934,1423531255, 8275108733,48511773461,286542497274,1704002332513, 10195435737315,61341136938138,370933387552634, 2253475545208390,13748639775492766, 84211761819147696] |