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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 15 |
| 6 | 31 |
| 7 | 64 |
| 8 | 155 |
| 9 | 717 |
| 10 | 6391 |
| 11 | 65010 |
| 12 | 629444 |
| 13 | 5719597 |
| 14 | 49340838 |
| 15 | 408864186 |
| 16 | 3284672489 |
| 17 | 25770192646 |
| 18 | 198718943490 |
| 19 | 1516391860879 |
| 20 | 11554571944615 |
| 21 | 89144035246500 |
| 22 | 711587142257776 |
| 23 | 6054854693784594 |
| 24 | 56609279400922224 |
| 25 | 590143167134961765 |
[0,0,1,3,7,15,31,64,155,717,6391,65010,629444, 5719597,49340838,408864186,3284672489,25770192646, 198718943490,1516391860879,11554571944615, 89144035246500,711587142257776,6054854693784594, 56609279400922224,590143167134961765] |