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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 16 |
| 3 | 82 |
| 4 | 416 |
| 5 | 2103 |
| 6 | 10633 |
| 7 | 53767 |
| 8 | 271882 |
| 9 | 1374808 |
| 10 | 6951884 |
| 11 | 35153031 |
| 12 | 177755487 |
| 13 | 898841773 |
| 14 | 4545100350 |
| 15 | 22982840520 |
| 16 | 116215466582 |
| 17 | 587657328849 |
| 18 | 2971559176087 |
| 19 | 15026042394605 |
| 20 | 75980970481664 |
| 21 | 384206813990810 |
[3,16,82,416,2103,10633,53767,271882,1374808, 6951884,35153031,177755487,898841773,4545100350, 22982840520,116215466582,587657328849, 2971559176087,15026042394605,75980970481664, 384206813990810] |