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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 66 |
| 5 | 518 |
| 6 | 4484 |
| 7 | 41424 |
| 8 | 399900 |
| 9 | 3983698 |
| 10 | 40622502 |
| 11 | 421780380 |
| 12 | 4442833776 |
| 13 | 47353725678 |
| 14 | 509717438804 |
| 15 | 5532808254500 |
| 16 | 60492412303032 |
| 17 | 665570138005230 |
| 18 | 7363717939202660 |
| 19 | 81872879608989990 |
| 20 | 914314572022052508 |
| 21 | 10251126194392776384 |
| 22 | 115346231108018654736 |
| 23 | 1302114832694059544892 |
[1,2,10,66,518,4484,41424,399900,3983698,40622502, 421780380,4442833776,47353725678,509717438804, 5532808254500,60492412303032,665570138005230, 7363717939202660,81872879608989990, 914314572022052508,10251126194392776384, 115346231108018654736,1302114832694059544892] |