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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 44 |
| 3 | 1028 |
| 4 | 40864 |
| 5 | 2484032 |
| 6 | 214050784 |
| 7 | 24831582176 |
| 8 | 3731039384576 |
| 9 | 704879630525696 |
| 10 | 163539441616948736 |
| 11 | 45712130697710081024 |
| 12 | 15150993151215400441856 |
| 13 | 5875388829103413298173952 |
| 14 | 2635427286694074346846232576 |
| 15 | 1353918066433734600362650169344 |
[1,4,44,1028,40864,2484032,214050784,24831582176, 3731039384576,704879630525696,163539441616948736, 45712130697710081024,15150993151215400441856, 5875388829103413298173952, 2635427286694074346846232576, 1353918066433734600362650169344] |