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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 31 |
| 6 | 103 |
| 7 | 351 |
| 8 | 1321 |
| 9 | 5113 |
| 10 | 21201 |
| 11 | 90465 |
| 12 | 406621 |
| 13 | 1879021 |
| 14 | 9051309 |
| 15 | 44754061 |
| 16 | 229059633 |
| 17 | 1201271409 |
| 18 | 6488957521 |
| 19 | 35853950609 |
| 20 | 203303964341 |
| 21 | 1177299817093 |
| 22 | 6976709899853 |
| 23 | 42161309544541 |
| 24 | 260154190137865 |
[1,1,2,4,11,31,103,351,1321,5113,21201,90465, 406621,1879021,9051309,44754061,229059633, 1201271409,6488957521,35853950609,203303964341, 1177299817093,6976709899853,42161309544541, 260154190137865] |