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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 2 |
| 3 | 3 |
| 4 | 7 |
| 5 | 16 |
| 6 | 41 |
| 7 | 112 |
| 8 | 318 |
| 9 | 922 |
| 10 | 2763 |
| 11 | 8394 |
| 12 | 25957 |
| 13 | 81172 |
| 14 | 256820 |
| 15 | 819114 |
| 16 | 2633626 |
| 17 | 8525056 |
| 18 | 27755962 |
| 19 | 90841159 |
| 20 | 298680608 |
| 21 | 986156342 |
| 22 | 3268174479 |
| 23 | 10867702340 |
| 24 | 36250205100 |
| 25 | 121257882210 |
| 26 | 406663900459 |
| 27 | 1367092812987 |
[2,2,3,7,16,41,112,318,922,2763,8394,25957,81172, 256820,819114,2633626,8525056,27755962,90841159, 298680608,986156342,3268174479,10867702340, 36250205100,121257882210,406663900459, 1367092812987] |