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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 17 |
| 3 | 140 |
| 4 | 2257 |
| 5 | 40766 |
| 6 | 206087 |
| 7 | 246853 |
| 8 | 452940 |
| 9 | 699793 |
| 10 | 1152733 |
| 11 | 8768924 |
| 12 | 9921657 |
| 13 | 18690581 |
| 14 | 122065143 |
| 15 | 262820867 |
| 16 | 2487452946 |
| 17 | 144535091735 |
| 18 | 147022544681 |
| 19 | 585602725778 |
| 20 | 2489433447793 |
| 21 | 5564469621364 |
| 22 | 13618372690521 |
[1,4,17,140,2257,40766,206087,246853,452940, 699793,1152733,8768924,9921657,18690581,122065143, 262820867,2487452946,144535091735,147022544681, 585602725778,2489433447793,5564469621364, 13618372690521] |