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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 12 |
| 3 | 19 |
| 4 | 258 |
| 5 | 1409 |
| 6 | 2836 |
| 7 | 48320 |
| 8 | 295092 |
| 9 | 629776 |
| 10 | 11499816 |
| 11 | 73045294 |
| 12 | 159683856 |
| 13 | 3012721252 |
| 14 | 19537447260 |
| 15 | 43276955012 |
| 16 | 832789320948 |
| 17 | 5471578311520 |
| 18 | 12222775051564 |
| 19 | 238366172778672 |
| 20 | 1580313985819656 |
| 21 | 3551105861275344 |
[3,12,19,258,1409,2836,48320,295092,629776, 11499816,73045294,159683856,3012721252, 19537447260,43276955012,832789320948, 5471578311520,12222775051564,238366172778672, 1580313985819656,3551105861275344] |