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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 33 |
| 5 | 28 |
| 6 | 165 |
| 7 | 54 |
| 8 | 1029 |
| 9 | 40832 |
| 10 | 31752 |
| 11 | 28680 |
| 12 | 2588680 |
| 13 | 2162700 |
| 14 | 12996613 |
| 15 | 12341252 |
| 16 | 4516741125 |
| 17 | 500367376 |
| 18 | 133207162881 |
| 19 | 93770874890 |
| 20 | 7043274506259 |
| 21 | 40985291653137 |
| 22 | 70766492123145 |
| 23 | 321901427163142 |
| 24 | 58731756479578128 |
| 25 | 676814631896875010 |
| 26 | 6820060161969750025 |
[1,4,9,33,28,165,54,1029,40832,31752,28680, 2588680,2162700,12996613,12341252,4516741125, 500367376,133207162881,93770874890,7043274506259, 40985291653137,70766492123145,321901427163142, 58731756479578128,676814631896875010, 6820060161969750025] |