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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 0 |
| 3 | 4 |
| 4 | 16 |
| 5 | 98 |
| 6 | 766 |
| 7 | 9982 |
| 8 | 205574 |
| 9 | 6546960 |
| 10 | 352380815 |
| 11 | 29668304472 |
| 12 | 4303531875334 |
| 13 | 985391751078694 |
| 14 | 391866509413730125 |
| 15 | 248491878411568471280 |
| 16 | 274544424465173973822126 |
| 17 | 488310442484985365942048784 |
| 18 | 1513516279388226700191978571979 |
[1,2,0,4,16,98,766,9982,205574,6546960,352380815, 29668304472,4303531875334,985391751078694, 391866509413730125,248491878411568471280, 274544424465173973822126, 488310442484985365942048784, 1513516279388226700191978571979] |