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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 19 |
| 4 | 299 |
| 5 | 6241 |
| 6 | 160020 |
| 7 | 4858616 |
| 8 | 171069361 |
| 9 | 6885389368 |
| 10 | 313162056098 |
| 11 | 15930678907603 |
| 12 | 897891292501468 |
| 13 | 55589209442827830 |
| 14 | 3751221859059876602 |
| 15 | 274034654053985700103 |
| 16 | 21542764404180713248407 |
| 17 | 1813058710831887654110832 |
| 18 | 162622164570756746546500432 |
| 19 | 15484376910535107858657060827 |
| 20 | 1559723646248351386009584065673 |
| 21 | 165693824812298090074580795882273 |
[1,1,2,19,299,6241,160020,4858616,171069361, 6885389368,313162056098,15930678907603, 897891292501468,55589209442827830, 3751221859059876602,274034654053985700103, 21542764404180713248407,1813058710831887654110832, 162622164570756746546500432, 15484376910535107858657060827, 1559723646248351386009584065673, 165693824812298090074580795882273] |