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) |
|---|---|
| 3 | 1 |
| 4 | 8 |
| 5 | 40 |
| 6 | 160 |
| 7 | 560 |
| 8 | 1792 |
| 9 | 5376 |
| 10 | 15360 |
| 11 | 42240 |
| 12 | 112640 |
| 13 | 292864 |
| 14 | 745472 |
| 15 | 1863680 |
| 16 | 4587520 |
| 17 | 11141120 |
| 18 | 26738688 |
| 19 | 63504384 |
| 20 | 149422080 |
| 21 | 348651520 |
| 22 | 807403520 |
| 23 | 1857028096 |
| 24 | 4244635648 |
| 25 | 9646899200 |
| 26 | 21810380800 |
| 27 | 49073356800 |
| 28 | 109924319232 |