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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 12 |
| 6 | 34 |
| 7 | 136 |
| 8 | 500 |
| 9 | 2440 |
| 10 | 10900 |
| 11 | 61912 |
| 12 | 322768 |
| 13 | 2075312 |
| 14 | 12297768 |
| 15 | 87852160 |
| 16 | 580849872 |
| 17 | 4548247264 |
| 18 | 33093252880 |
| 19 | 281121815712 |
| 20 | 2227152575552 |
| 21 | 20358402201792 |
| 22 | 174131286983712 |
| 23 | 1701534399324544 |
| 24 | 15604440074084672 |
[1,1,2,4,12,34,136,500,2440,10900,61912,322768, 2075312,12297768,87852160,580849872,4548247264, 33093252880,281121815712,2227152575552, 20358402201792,174131286983712,1701534399324544, 15604440074084672] |