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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 97 |
| 6 | 336 |
| 7 | 1153 |
| 8 | 4081 |
| 9 | 14552 |
| 10 | 52609 |
| 11 | 191657 |
| 12 | 704385 |
| 13 | 2604476 |
| 14 | 9687433 |
| 15 | 36207241 |
| 16 | 135920489 |
| 17 | 512182805 |
| 18 | 1936656361 |
| 19 | 7345211322 |
| 20 | 27935373368 |
| 21 | 106509551719 |
| 22 | 407015199144 |
| 23 | 1558603221623 |
| 24 | 5979839952471 |
| 25 | 22983021033071 |
| 26 | 88477003979994 |
| 27 | 341120527468590 |
[1,1,3,9,30,97,336,1153,4081,14552,52609,191657, 704385,2604476,9687433,36207241,135920489, 512182805,1936656361,7345211322,27935373368, 106509551719,407015199144,1558603221623, 5979839952471,22983021033071,88477003979994, 341120527468590] |