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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 46 |
| 6 | 172 |
| 7 | 651 |
| 8 | 2478 |
| 9 | 9457 |
| 10 | 36228 |
| 11 | 139249 |
| 12 | 536687 |
| 13 | 2073540 |
| 14 | 8028826 |
| 15 | 31147792 |
| 16 | 121045410 |
| 17 | 471128566 |
| 18 | 1836259944 |
| 19 | 7165975248 |
| 20 | 27997121205 |
| 21 | 109497724812 |
| 22 | 428659516902 |
| 23 | 1679585156639 |
| 24 | 6586339566777 |
| 25 | 25847132064141 |
[1,1,3,12,46,172,651,2478,9457,36228,139249, 536687,2073540,8028826,31147792,121045410, 471128566,1836259944,7165975248,27997121205, 109497724812,428659516902,1679585156639, 6586339566777,25847132064141] |