This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 2 | 0 |
| 3 | 3 |
| 4 | 12 |
| 5 | 80 |
| 6 | 840 |
| 7 | 630 |
| 8 | 13440 |
| 9 | 277200 |
| 10 | 75600 |
| 11 | 3326400 |
| 12 | 116839800 |
| 13 | 16216200 |
| 14 | 1210809600 |
| 15 | 65043178200 |
| 16 | 5448643200 |
| 17 | 617512896000 |
| 18 | 47147109609600 |
| 19 | 2639867630400 |
| 20 | 422378820864000 |
| 21 | 43505018548992000 |
| 22 | 1742312636064000 |
| 23 | 374016445875072000 |
| 24 | 49991305310266320000 |
| 25 | 1502744648605200000 |