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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 17 |
| 4 | 51 |
| 5 | 149 |
| 6 | 439 |
| 7 | 1308 |
| 8 | 3916 |
| 9 | 11728 |
| 10 | 35093 |
| 11 | 104943 |
| 12 | 313773 |
| 13 | 938199 |
| 14 | 2805439 |
| 15 | 8389163 |
| 16 | 25086356 |
| 17 | 75016104 |
| 18 | 224321012 |
| 19 | 670787533 |
| 20 | 2005857561 |
| 21 | 5998122649 |
| 22 | 17936209267 |
| 23 | 53634716681 |
| 24 | 160384099011 |
| 25 | 479597177352 |
| 26 | 1434141243492 |
| 27 | 4288517958652 |
[0,1,5,17,51,149,439,1308,3916,11728,35093,104943, 313773,938199,2805439,8389163,25086356,75016104, 224321012,670787533,2005857561,5998122649, 17936209267,53634716681,160384099011,479597177352, 1434141243492,4288517958652] |