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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 18 |
| 4 | 62 |
| 5 | 217 |
| 6 | 818 |
| 7 | 3121 |
| 8 | 12381 |
| 9 | 49571 |
| 10 | 203049 |
| 11 | 839400 |
| 12 | 3521390 |
| 13 | 14897035 |
| 14 | 63638310 |
| 15 | 273791526 |
| 16 | 1186143557 |
| 17 | 5169379953 |
| 18 | 22649963428 |
| 19 | 99731867420 |
| 20 | 441044844823 |
| 21 | 1958337923511 |
| 22 | 8726940635121 |
| 23 | 39020752850638 |
| 24 | 175010536790968 |
| 25 | 787164676052659 |
| 26 | 3549874609418846 |
| 27 | 16047893490021657 |
[1,2,6,18,62,217,818,3121,12381,49571,203049, 839400,3521390,14897035,63638310,273791526, 1186143557,5169379953,22649963428,99731867420, 441044844823,1958337923511,8726940635121, 39020752850638,175010536790968,787164676052659, 3549874609418846,16047893490021657] |