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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 50 |
| 5 | 257 |
| 6 | 1467 |
| 7 | 9081 |
| 8 | 60272 |
| 9 | 424514 |
| 10 | 3151226 |
| 11 | 24510411 |
| 12 | 198870388 |
| 13 | 1676878231 |
| 14 | 14648843341 |
| 15 | 132228263355 |
| 16 | 1230505582380 |
| 17 | 11782173683640 |
| 18 | 115878367974480 |
| 19 | 1168833058344870 |
| 20 | 12075008262774120 |
| 21 | 127608480923659770 |
[1,1,3,11,50,257,1467,9081,60272,424514,3151226, 24510411,198870388,1676878231,14648843341, 132228263355,1230505582380,11782173683640, 115878367974480,1168833058344870, 12075008262774120,127608480923659770] |