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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 352 |
| 3 | 9909 |
| 4 | 107776 |
| 5 | 698125 |
| 6 | 3252096 |
| 7 | 12045817 |
| 8 | 37679104 |
| 9 | 103495401 |
| 10 | 256420000 |
| 11 | 584190541 |
| 12 | 1241471232 |
| 13 | 2487920149 |
| 14 | 4741917376 |
| 15 | 8654360625 |
| 16 | 15207694336 |
| 17 | 25846158097 |
| 18 | 42644120544 |
| 19 | 68520305701 |
| 20 | 107506720000 |
| 21 | 165082149981 |
| 22 | 248581222912 |
| 23 | 367691205289 |
[0,1,352,9909,107776,698125,3252096,12045817, 37679104,103495401,256420000,584190541,1241471232, 2487920149,4741917376,8654360625,15207694336, 25846158097,42644120544,68520305701,107506720000, 165082149981,248581222912,367691205289] |