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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 41 |
| 3 | 285 |
| 4 | 1989 |
| 5 | 13901 |
| 6 | 97215 |
| 7 | 680079 |
| 8 | 4758408 |
| 9 | 33297267 |
| 10 | 233014444 |
| 11 | 1630701426 |
| 12 | 11412409945 |
| 13 | 79870754268 |
| 14 | 558989013403 |
| 15 | 3912210491549 |
| 16 | 27380636068267 |
| 17 | 191631324294463 |
| 18 | 1341190961828143 |
| 19 | 9386756237545989 |
[1,6,41,285,1989,13901,97215,680079,4758408, 33297267,233014444,1630701426,11412409945, 79870754268,558989013403,3912210491549, 27380636068267,191631324294463,1341190961828143, 9386756237545989] |