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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 88 |
| 6 | 364 |
| 7 | 1522 |
| 8 | 6374 |
| 9 | 26640 |
| 10 | 110980 |
| 11 | 460716 |
| 12 | 1906172 |
| 13 | 7862416 |
| 14 | 32341144 |
| 15 | 132707626 |
| 16 | 543376774 |
| 17 | 2220650656 |
| 18 | 9060011284 |
| 19 | 36908739316 |
| 20 | 150159618964 |
| 21 | 610186287376 |
| 22 | 2476912674664 |
| 23 | 10044874544116 |
| 24 | 40700948789212 |
| 25 | 164788263075808 |
| 26 | 666716080038824 |
[1,2,6,22,88,364,1522,6374,26640,110980,460716, 1906172,7862416,32341144,132707626,543376774, 2220650656,9060011284,36908739316,150159618964, 610186287376,2476912674664,10044874544116, 40700948789212,164788263075808,666716080038824] |