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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 93 |
| 4 | 621 |
| 5 | 4263 |
| 6 | 29595 |
| 7 | 206433 |
| 8 | 1442841 |
| 9 | 10093323 |
| 10 | 70633575 |
| 11 | 494375973 |
| 12 | 3460454661 |
| 13 | 24222651183 |
| 14 | 169556963955 |
| 15 | 1186893964713 |
| 16 | 8308243404081 |
| 17 | 58157660781843 |
| 18 | 407103496332735 |
| 19 | 2849724086908653 |
| 20 | 19948067446099101 |
[1,3,15,93,621,4263,29595,206433,1442841,10093323, 70633575,494375973,3460454661,24222651183, 169556963955,1186893964713,8308243404081, 58157660781843,407103496332735,2849724086908653, 19948067446099101] |