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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 12 |
| 3 | 75 |
| 4 | 364 |
| 5 | 1581 |
| 6 | 6540 |
| 7 | 26503 |
| 8 | 106524 |
| 9 | 426825 |
| 10 | 1708300 |
| 11 | 6834531 |
| 12 | 27339852 |
| 13 | 109361605 |
| 14 | 437449164 |
| 15 | 1749800031 |
| 16 | 6999204220 |
| 17 | 27996821793 |
| 18 | 111987293004 |
| 19 | 447949178875 |
| 20 | 1791796723500 |
| 21 | 7167186903261 |
| 22 | 28668747623692 |
| 23 | 114674990506935 |
| 24 | 458699962041564 |
[0,1,12,75,364,1581,6540,26503,106524,426825, 1708300,6834531,27339852,109361605,437449164, 1749800031,6999204220,27996821793,111987293004, 447949178875,1791796723500,7167186903261, 28668747623692,114674990506935,458699962041564] |