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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 36 |
| 6 | 142 |
| 7 | 647 |
| 8 | 3383 |
| 9 | 19816 |
| 10 | 129162 |
| 11 | 923279 |
| 12 | 7201951 |
| 13 | 60720996 |
| 14 | 551268926 |
| 15 | 5352973967 |
| 16 | 55430433719 |
| 17 | 609033864160 |
| 18 | 7083303687843 |
| 19 | 86864585123112 |
| 20 | 1120997775904467 |
| 21 | 15176639841694385 |
| 22 | 215196709973260722 |
| 23 | 3187766448289854016 |
| 24 | 49262381105608795771 |
[1,1,2,4,11,36,142,647,3383,19816,129162,923279, 7201951,60720996,551268926,5352973967,55430433719, 609033864160,7083303687843,86864585123112, 1120997775904467,15176639841694385, 215196709973260722,3187766448289854016, 49262381105608795771] |