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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 19 |
| 5 | 50 |
| 6 | 130 |
| 7 | 341 |
| 8 | 893 |
| 9 | 2337 |
| 10 | 6119 |
| 11 | 16020 |
| 12 | 41940 |
| 13 | 109801 |
| 14 | 287463 |
| 15 | 752587 |
| 16 | 1970299 |
| 17 | 5158310 |
| 18 | 13504630 |
| 19 | 35355581 |
| 20 | 92562113 |
| 21 | 242330757 |
| 22 | 634430159 |
| 23 | 1660959720 |
| 24 | 4348449000 |
| 25 | 11384387281 |
| 26 | 29804712843 |
| 27 | 78029751247 |
| 28 | 204284540899 |
[0,1,3,7,19,50,130,341,893,2337,6119,16020,41940, 109801,287463,752587,1970299,5158310,13504630, 35355581,92562113,242330757,634430159,1660959720, 4348449000,11384387281,29804712843,78029751247, 204284540899] |