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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 28 |
| 3 | 326 |
| 4 | 5702 |
| 5 | 136724 |
| 6 | 4226334 |
| 7 | 161385532 |
| 8 | 7378504140 |
| 9 | 394404094270 |
| 10 | 24193638303234 |
| 11 | 1677962100799727 |
| 12 | 129990908689219749 |
| 13 | 11135889051081255518 |
| 14 | 1046032727101344902679 |
| 15 | 106966601176207198837104 |
[1,4,28,326,5702,136724,4226334,161385532, 7378504140,394404094270,24193638303234, 1677962100799727,129990908689219749, 11135889051081255518,1046032727101344902679, 106966601176207198837104] |