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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 49 |
| 5 | 175 |
| 6 | 655 |
| 7 | 2437 |
| 8 | 9208 |
| 9 | 34867 |
| 10 | 132952 |
| 11 | 508621 |
| 12 | 1953580 |
| 13 | 7524625 |
| 14 | 29061835 |
| 15 | 112493680 |
| 16 | 436330753 |
| 17 | 1695388480 |
| 18 | 6598016866 |
| 19 | 25714222228 |
| 20 | 100343852938 |
| 21 | 392023844362 |
| 22 | 1533182752336 |
| 23 | 6001993189687 |
| 24 | 23517048084424 |
| 25 | 92220047277892 |
| 26 | 361906295452669 |
| 27 | 1421252193947311 |
[1,1,4,13,49,175,655,2437,9208,34867,132952, 508621,1953580,7524625,29061835,112493680, 436330753,1695388480,6598016866,25714222228, 100343852938,392023844362,1533182752336, 6001993189687,23517048084424,92220047277892, 361906295452669,1421252193947311] |