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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 42 |
| 5 | 260 |
| 6 | 1808 |
| 7 | 13744 |
| 8 | 112290 |
| 9 | 974880 |
| 10 | 8922276 |
| 11 | 85580496 |
| 12 | 856495752 |
| 13 | 8913100944 |
| 14 | 96181220816 |
| 15 | 1073829057728 |
| 16 | 12380935349458 |
| 17 | 147183697957428 |
| 18 | 1801623160794480 |
| 19 | 22680386387491816 |
| 20 | 293333571234859004 |
| 21 | 3893918653806360608 |
| 22 | 53009297608751805168 |
| 23 | 739458889943201941584 |
| 24 | 10562209578309277545672 |
[1,2,8,42,260,1808,13744,112290,974880,8922276, 85580496,856495752,8913100944,96181220816, 1073829057728,12380935349458,147183697957428, 1801623160794480,22680386387491816, 293333571234859004,3893918653806360608, 53009297608751805168,739458889943201941584, 10562209578309277545672] |