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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 17 |
| 5 | 41 |
| 6 | 97 |
| 7 | 253 |
| 8 | 673 |
| 9 | 1745 |
| 10 | 4481 |
| 11 | 11573 |
| 12 | 30001 |
| 13 | 77689 |
| 14 | 200929 |
| 15 | 519725 |
| 16 | 1344833 |
| 17 | 3479969 |
| 18 | 9004033 |
| 19 | 23296357 |
| 20 | 60276817 |
| 21 | 155961545 |
| 22 | 403535969 |
| 23 | 1044107357 |
| 24 | 2701521889 |
| 25 | 6989923441 |
| 26 | 18085741441 |
| 27 | 46795063445 |
| 28 | 121077583217 |
[1,1,1,5,17,41,97,253,673,1745,4481,11573,30001, 77689,200929,519725,1344833,3479969,9004033, 23296357,60276817,155961545,403535969,1044107357, 2701521889,6989923441,18085741441,46795063445, 121077583217] |