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) |
|---|---|
| 1 | 4 |
| 2 | 12 |
| 3 | 60 |
| 4 | 180 |
| 5 | 420 |
| 6 | 5100 |
| 7 | 60900 |
| 8 | 135720 |
| 9 | 161880 |
| 10 | 163020 |
| 11 | 218460 |
| 12 | 595140 |
| 13 | 1108560 |
| 14 | 2574180 |
| 15 | 2740140 |
| 16 | 3248700 |
| 17 | 3535140 |
| 18 | 3723720 |
| 19 | 3729180 |
| 20 | 8197200 |
| 21 | 13933920 |
| 22 | 20218440 |
| 23 | 23605320 |
| 24 | 28569240 |
| 25 | 33874680 |
| 26 | 47248920 |
| 27 | 68667480 |
| 28 | 69372420 |