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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 13 |
| 3 | 67 |
| 4 | 381 |
| 5 | 2307 |
| 6 | 14589 |
| 7 | 95235 |
| 8 | 636925 |
| 9 | 4341763 |
| 10 | 30056445 |
| 11 | 210731011 |
| 12 | 1493303293 |
| 13 | 10678370307 |
| 14 | 76957679613 |
| 15 | 558403682307 |
| 16 | 4075996839933 |
| 17 | 29909606989827 |
| 18 | 220510631755773 |
| 19 | 1632599134961667 |
| 20 | 12133359132082173 |
[1,3,13,67,381,2307,14589,95235,636925,4341763, 30056445,210731011,1493303293,10678370307, 76957679613,558403682307,4075996839933, 29909606989827,220510631755773,1632599134961667, 12133359132082173] |