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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 53 |
| 5 | 235 |
| 6 | 2709 |
| 7 | 20188 |
| 8 | 278249 |
| 9 | 3019693 |
| 10 | 48281695 |
| 11 | 692436338 |
| 12 | 12717929157 |
| 13 | 225943945071 |
| 14 | 4727712830281 |
| 15 | 99660715587704 |
| 16 | 2354596166060273 |
| 17 | 57197420701626009 |
| 18 | 1511830772603161339 |
[1,1,3,6,53,235,2709,20188,278249,3019693, 48281695,692436338,12717929157,225943945071, 4727712830281,99660715587704,2354596166060273, 57197420701626009,1511830772603161339] |