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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 15 |
| 6 | 49 |
| 7 | 180 |
| 8 | 701 |
| 9 | 2891 |
| 10 | 12371 |
| 11 | 54564 |
| 12 | 246319 |
| 13 | 1133602 |
| 14 | 5300255 |
| 15 | 25119554 |
| 16 | 120441076 |
| 17 | 583373822 |
| 18 | 2851023191 |
| 19 | 14044428996 |
| 20 | 69677569603 |
| 21 | 347904448580 |
| 22 | 1747195558582 |
| 23 | 8820848574074 |
| 24 | 44747514381341 |
| 25 | 228004950808983 |
| 26 | 1166498678253839 |
| 27 | 5990376960443432 |
[1,1,2,5,15,49,180,701,2891,12371,54564,246319, 1133602,5300255,25119554,120441076,583373822, 2851023191,14044428996,69677569603,347904448580, 1747195558582,8820848574074,44747514381341, 228004950808983,1166498678253839,5990376960443432] |