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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 5 |
| 5 | 12 |
| 6 | 42 |
| 7 | 136 |
| 8 | 602 |
| 9 | 2440 |
| 10 | 12840 |
| 11 | 61912 |
| 12 | 373780 |
| 13 | 2075312 |
| 14 | 14050312 |
| 15 | 87852160 |
| 16 | 656404264 |
| 17 | 4548247264 |
| 18 | 37060650272 |
| 19 | 281121815712 |
| 20 | 2475181138384 |
| 21 | 20358402201792 |
| 22 | 192262536609952 |
| 23 | 1701534399324544 |
| 24 | 17131843186425504 |
[1,2,2,5,12,42,136,602,2440,12840,61912,373780, 2075312,14050312,87852160,656404264,4548247264, 37060650272,281121815712,2475181138384, 20358402201792,192262536609952,1701534399324544, 17131843186425504] |