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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 26 |
| 4 | 136 |
| 5 | 4219 |
| 6 | 114514 |
| 7 | 5074646 |
| 8 | 681913008 |
| 9 | 140688693646 |
| 10 | 48442426003864 |
| 11 | 36951311160860211 |
[1,4,26,136,4219,114514,5074646,681913008, 140688693646,48442426003864,36951311160860211] |