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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 20 |
| 4 | 148 |
| 5 | 2208 |
| 6 | 67904 |
| 7 | 4264960 |
| 8 | 541216768 |
| 9 | 137984868352 |
| 10 | 70507295670272 |
| 11 | 72128242290524160 |
| 12 | 147646152060442771456 |
| 13 | 604610628447525580832768 |
| 14 | 4952364915780360673188380672 |
| 15 | 81134591384874923825347187179520 |
[1,2,5,20,148,2208,67904,4264960,541216768, 137984868352,70507295670272,72128242290524160, 147646152060442771456,604610628447525580832768, 4952364915780360673188380672, 81134591384874923825347187179520] |