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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 15 |
| 3 | 183 |
| 4 | 953 |
| 5 | 7799 |
| 6 | 58661 |
| 7 | 416291 |
| 8 | 3109443 |
| 9 | 22837977 |
| 10 | 167468295 |
| 11 | 1233723835 |
| 12 | 9067625183 |
| 13 | 66666846231 |
| 14 | 490306244985 |
| 15 | 3605057176121 |
| 16 | 26508858876345 |
| 17 | 194928358871853 |
| 18 | 1433337703487151 |
| 19 | 10539668947354103 |
| 20 | 77500564655649379 |
[1,15,183,953,7799,58661,416291,3109443,22837977, 167468295,1233723835,9067625183,66666846231, 490306244985,3605057176121,26508858876345, 194928358871853,1433337703487151, 10539668947354103,77500564655649379] |