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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 7 |
| 5 | 16 |
| 6 | 43 |
| 7 | 123 |
| 8 | 384 |
| 9 | 1283 |
| 10 | 4575 |
| 11 | 17294 |
| 12 | 69013 |
| 13 | 289613 |
| 14 | 1273934 |
| 15 | 5856811 |
| 16 | 28070535 |
| 17 | 139936316 |
| 18 | 724141487 |
| 19 | 3882776711 |
| 20 | 21536499372 |
| 21 | 123388080843 |
| 22 | 729195916303 |
| 23 | 4439611287834 |
| 24 | 27814781772073 |
| 25 | 179132776279001 |
| 26 | 1184720299683034 |
| 27 | 8038979166269203 |
[1,1,2,3,7,16,43,123,384,1283,4575,17294,69013, 289613,1273934,5856811,28070535,139936316, 724141487,3882776711,21536499372,123388080843, 729195916303,4439611287834,27814781772073, 179132776279001,1184720299683034,8038979166269203] |