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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 46 |
| 5 | 163 |
| 6 | 691 |
| 7 | 2761 |
| 8 | 11734 |
| 9 | 50199 |
| 10 | 218371 |
| 11 | 964109 |
| 12 | 4274622 |
| 13 | 19172727 |
| 14 | 86702998 |
| 15 | 393870617 |
| 16 | 1804068528 |
| 17 | 8280505767 |
| 18 | 38258694113 |
| 19 | 177369807157 |
| 20 | 825171442348 |
| 21 | 3854248987491 |
| 22 | 18039911515304 |
| 23 | 84739900425283 |
| 24 | 398932218327032 |
| 25 | 1882432029832379 |
| 26 | 8904366161915705 |
| 27 | 42187531241280899 |
[1,1,4,11,46,163,691,2761,11734,50199,218371, 964109,4274622,19172727,86702998,393870617, 1804068528,8280505767,38258694113,177369807157, 825171442348,3854248987491,18039911515304, 84739900425283,398932218327032,1882432029832379, 8904366161915705,42187531241280899] |