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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 1 |
| 4 | 4 |
| 5 | 6 |
| 6 | 36 |
| 7 | 117 |
| 8 | 804 |
| 9 | 4266 |
| 10 | 33768 |
| 11 | 249144 |
| 12 | 2289348 |
| 13 | 21353472 |
| 14 | 227212824 |
| 15 | 2533824900 |
| 16 | 30914509212 |
| 17 | 398623158096 |
| 18 | 5508014798052 |
| 19 | 80377645583430 |
| 20 | 1242697826967816 |
| 21 | 20218588415853480 |
| 22 | 346035438765576720 |
| 23 | 6206862951272939550 |
| 24 | 116518581654518098332 |
[1,1,2,1,4,6,36,117,804,4266,33768,249144,2289348, 21353472,227212824,2533824900,30914509212, 398623158096,5508014798052,80377645583430, 1242697826967816,20218588415853480, 346035438765576720,6206862951272939550, 116518581654518098332] |