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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 14 |
| 6 | 41 |
| 7 | 124 |
| 8 | 385 |
| 9 | 1220 |
| 10 | 3929 |
| 11 | 12822 |
| 12 | 42309 |
| 13 | 140922 |
| 14 | 473169 |
| 15 | 1599864 |
| 16 | 5442561 |
| 17 | 18615176 |
| 18 | 63975857 |
| 19 | 220816906 |
| 20 | 765121477 |
| 21 | 2660426630 |
| 22 | 9280204025 |
| 23 | 32466050612 |
| 24 | 113883898241 |
| 25 | 400464335116 |
| 26 | 1411407234697 |
| 27 | 4984885122974 |
[1,1,2,5,14,41,124,385,1220,3929,12822,42309, 140922,473169,1599864,5442561,18615176,63975857, 220816906,765121477,2660426630,9280204025, 32466050612,113883898241,400464335116, 1411407234697,4984885122974] |