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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 14 |
| 5 | 53 |
| 6 | 180 |
| 7 | 656 |
| 8 | 2195 |
| 9 | 7250 |
| 10 | 23044 |
| 11 | 71123 |
| 12 | 213368 |
| 13 | 624425 |
| 14 | 1784399 |
| 15 | 4986210 |
| 16 | 13657266 |
| 17 | 36691985 |
| 18 | 96863639 |
| 19 | 251472815 |
| 20 | 642811767 |
| 21 | 1619203005 |
| 22 | 4022796235 |
| 23 | 9864987052 |
| 24 | 23894800443 |
| 25 | 57205375668 |
| 26 | 135438579331 |
| 27 | 317296680619 |
[1,2,4,14,53,180,656,2195,7250,23044,71123,213368, 624425,1784399,4986210,13657266,36691985,96863639, 251472815,642811767,1619203005,4022796235, 9864987052,23894800443,57205375668,135438579331, 317296680619] |