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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 73 |
| 5 | 561 |
| 6 | 4771 |
| 7 | 49813 |
| 8 | 562353 |
| 9 | 7340833 |
| 10 | 102829411 |
| 11 | 1627648221 |
| 12 | 27294311353 |
| 13 | 502042022353 |
| 14 | 9759264753603 |
| 15 | 205434011254501 |
| 16 | 4544894700204001 |
| 17 | 107346788357502273 |
| 18 | 2657668122191037763 |
| 19 | 69701762677026498733 |
| 20 | 1909106308252976007081 |
[1,1,3,13,73,561,4771,49813,562353,7340833, 102829411,1627648221,27294311353,502042022353, 9759264753603,205434011254501,4544894700204001, 107346788357502273,2657668122191037763, 69701762677026498733,1909106308252976007081] |