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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 12 |
| 5 | 33 |
| 6 | 87 |
| 7 | 227 |
| 8 | 583 |
| 9 | 1538 |
| 10 | 4067 |
| 11 | 10633 |
| 12 | 27837 |
| 13 | 72387 |
| 14 | 188811 |
| 15 | 493437 |
| 16 | 1288622 |
| 17 | 3355810 |
| 18 | 8740288 |
| 19 | 22783725 |
| 20 | 59403150 |
| 21 | 154824944 |
| 22 | 403509362 |
| 23 | 1051651919 |
| 24 | 2740858097 |
| 25 | 7144656505 |
| 26 | 18623531350 |
| 27 | 48542955448 |
| 28 | 126526434447 |
[1,2,5,12,33,87,227,583,1538,4067,10633,27837, 72387,188811,493437,1288622,3355810,8740288, 22783725,59403150,154824944,403509362,1051651919, 2740858097,7144656505,18623531350,48542955448, 126526434447] |