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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 37 |
| 3 | 143 |
| 4 | 627 |
| 5 | 2767 |
| 6 | 11345 |
| 7 | 51706 |
| 8 | 223151 |
| 9 | 974387 |
| 10 | 4317835 |
| 11 | 18935262 |
| 12 | 83405497 |
| 13 | 367312087 |
| 14 | 1616039971 |
| 15 | 7119896616 |
| 16 | 31348982360 |
| 17 | 138041608632 |
| 18 | 607987526596 |
| 19 | 2677387312069 |
| 20 | 11791160763537 |
| 21 | 51928980096226 |
| 22 | 228692213910063 |
[4,37,143,627,2767,11345,51706,223151,974387, 4317835,18935262,83405497,367312087,1616039971, 7119896616,31348982360,138041608632,607987526596, 2677387312069,11791160763537,51928980096226, 228692213910063] |