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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 10 |
| 5 | 17 |
| 6 | 38 |
| 7 | 106 |
| 8 | 253 |
| 9 | 716 |
| 10 | 1903 |
| 11 | 5053 |
| 12 | 13786 |
| 13 | 39293 |
| 14 | 107641 |
| 15 | 302807 |
| 16 | 860099 |
| 17 | 2450684 |
| 18 | 7038472 |
| 19 | 20316895 |
| 20 | 58849665 |
| 21 | 171217429 |
| 22 | 499926666 |
| 23 | 1464276207 |
| 24 | 4301706250 |
| 25 | 12671810107 |
| 26 | 37419912977 |
| 27 | 110759884262 |
| 28 | 328525197554 |
[1,1,3,10,17,38,106,253,716,1903,5053,13786,39293, 107641,302807,860099,2450684,7038472,20316895, 58849665,171217429,499926666,1464276207, 4301706250,12671810107,37419912977,110759884262, 328525197554] |