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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 25 |
| 5 | 61 |
| 6 | 211 |
| 7 | 841 |
| 8 | 2857 |
| 9 | 9745 |
| 10 | 36421 |
| 11 | 134971 |
| 12 | 488731 |
| 13 | 1807807 |
| 14 | 6788965 |
| 15 | 25384087 |
| 16 | 95114377 |
| 17 | 359291737 |
| 18 | 1361265889 |
| 19 | 5162682775 |
| 20 | 19642369405 |
| 21 | 74960720065 |
| 22 | 286563664135 |
| 23 | 1097430871285 |
| 24 | 4211301910795 |
| 25 | 16187715501811 |
| 26 | 62311953400711 |
| 27 | 240203420513161 |
[1,1,1,7,25,61,211,841,2857,9745,36421,134971, 488731,1807807,6788965,25384087,95114377, 359291737,1361265889,5162682775,19642369405, 74960720065,286563664135,1097430871285, 4211301910795,16187715501811,62311953400711, 240203420513161] |