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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 180 |
| 5 | 2640 |
| 6 | 52934 |
| 7 | 1307556 |
| 8 | 39067428 |
| 9 | 1369499060 |
| 10 | 54995284784 |
| 11 | 2507211396061 |
| 12 | 127388480252917 |
| 13 | 7144814127814222 |
| 14 | 439553511977812220 |
| 15 | 29347225935730588372 |
| 16 | 2116793087420823777580 |
| 17 | 164035715631344596393196 |
[1,1,3,16,180,2640,52934,1307556,39067428, 1369499060,54995284784,2507211396061, 127388480252917,7144814127814222, 439553511977812220,29347225935730588372, 2116793087420823777580,164035715631344596393196] |