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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 21 |
| 5 | 53 |
| 6 | 197 |
| 7 | 568 |
| 8 | 2232 |
| 9 | 6840 |
| 10 | 27846 |
| 11 | 90222 |
| 12 | 375296 |
| 13 | 1259121 |
| 14 | 5332794 |
| 15 | 18418518 |
| 16 | 78879842 |
| 17 | 279015843 |
| 18 | 1207434736 |
| 19 | 4346911083 |
| 20 | 18965926422 |
| 21 | 69405012659 |
| 22 | 304800551773 |
| 23 | 1129759333245 |
| 24 | 4991666096752 |
| 25 | 18713425012565 |
| 26 | 83069381842542 |
| 27 | 314547432379660 |
| 28 | 1402401681255811 |
| 29 | 5355172458948690 |
[1,1,3,6,21,53,197,568,2232,6840,27846,90222, 375296,1259121,5332794,18418518,78879842, 279015843,1207434736,4346911083,18965926422, 69405012659,304800551773,1129759333245, 4991666096752,18713425012565,83069381842542, 314547432379660,1402401681255811,5355172458948690] |