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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 52 |
| 6 | 208 |
| 7 | 800 |
| 8 | 3360 |
| 9 | 14024 |
| 10 | 55492 |
| 11 | 223040 |
| 12 | 900728 |
| 13 | 3560916 |
| 14 | 14099980 |
| 15 | 56141676 |
| 16 | 222623336 |
| 17 | 881949584 |
| 18 | 3502057736 |
| 19 | 13900013276 |
| 20 | 55132695636 |
| 21 | 218842222824 |
| 22 | 868762179984 |
| 23 | 3447429959044 |
| 24 | 13682419728976 |
| 25 | 54311665765692 |
[1,2,6,16,52,208,800,3360,14024,55492,223040, 900728,3560916,14099980,56141676,222623336, 881949584,3502057736,13900013276,55132695636, 218842222824,868762179984,3447429959044, 13682419728976,54311665765692] |