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| n | a(n) |
|---|---|
| 1 | 20 |
| 2 | 74 |
| 3 | 212 |
| 4 | 828 |
| 5 | 2312 |
| 6 | 9178 |
| 7 | 25652 |
| 8 | 102356 |
| 9 | 287960 |
| 10 | 1150916 |
| 11 | 3260168 |
| 12 | 13037240 |
| 13 | 37151120 |
| 14 | 148591610 |
| 15 | 425537780 |
| 16 | 1702102500 |
| 17 | 4894629560 |
| 18 | 19578333484 |
| 19 | 56494758872 |
| 20 | 225978330056 |
| 21 | 653985816944 |
| 22 | 2615940563620 |
| 23 | 7589574333512 |
[20,74,212,828,2312,9178,25652,102356,287960, 1150916,3260168,13037240,37151120,148591610, 425537780,1702102500,4894629560,19578333484, 56494758872,225978330056,653985816944, 2615940563620,7589574333512] |