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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 73 |
| 6 | 233 |
| 7 | 677 |
| 8 | 1819 |
| 9 | 4606 |
| 10 | 11171 |
| 11 | 26274 |
| 12 | 60471 |
| 13 | 137059 |
| 14 | 307245 |
| 15 | 683171 |
| 16 | 1509595 |
| 17 | 3319028 |
| 18 | 7266583 |
| 19 | 15850872 |
| 20 | 34462295 |
| 21 | 74700801 |
| 22 | 161470161 |
| 23 | 348116785 |
| 24 | 748673435 |
| 25 | 1606409882 |
| 26 | 3439322827 |
| 27 | 7348417246 |
| 28 | 15669920663 |
| 29 | 33353112015 |
[1,2,6,21,73,233,677,1819,4606,11171,26274,60471, 137059,307245,683171,1509595,3319028,7266583, 15850872,34462295,74700801,161470161,348116785, 748673435,1606409882,3439322827,7348417246, 15669920663,33353112015] |