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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 27 |
| 5 | 540 |
| 6 | 2002 |
| 7 | 10660 |
| 8 | 39501 |
| 9 | 779247 |
| 10 | 2887450 |
| 11 | 15372280 |
| 12 | 56960982 |
| 13 | 1123674201 |
| 14 | 4163701465 |
| 15 | 22166817667 |
| 16 | 82137697110 |
| 17 | 1620337419162 |
| 18 | 6004054625647 |
| 19 | 31964535704101 |
| 20 | 118442502272205 |
| 21 | 2336525434757970 |
| 22 | 8657842606482076 |
| 23 | 46092838318496542 |
[0,1,7,27,540,2002,10660,39501,779247,2887450, 15372280,56960982,1123674201,4163701465, 22166817667,82137697110,1620337419162, 6004054625647,31964535704101,118442502272205, 2336525434757970,8657842606482076, 46092838318496542] |