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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 240 |
| 2 | 10920 |
| 3 | 163520 |
| 4 | 1075860 |
| 5 | 4464096 |
| 6 | 14909440 |
| 7 | 40080000 |
| 8 | 96643950 |
| 9 | 204728400 |
| 10 | 412819680 |
| 11 | 754303680 |
| 12 | 1350075720 |
| 13 | 2236728480 |
| 14 | 3673313280 |
| 15 | 5666507392 |
| 16 | 8760753540 |
| 17 | 12779981760 |
| 18 | 18827053960 |
| 19 | 26351976000 |
| 20 | 37332319752 |
| 21 | 50483661760 |
| 22 | 69411962880 |
| 23 | 91160284800 |
| 24 | 122167955000 |
[1,240,10920,163520,1075860,4464096,14909440, 40080000,96643950,204728400,412819680,754303680, 1350075720,2236728480,3673313280,5666507392, 8760753540,12779981760,18827053960,26351976000, 37332319752,50483661760,69411962880,91160284800, 122167955000] |