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 | 24 |
| 4 | 72 |
| 5 | 120 |
| 6 | 408 |
| 7 | 840 |
| 8 | 2448 |
| 9 | 5760 |
| 10 | 15960 |
| 11 | 39864 |
| 12 | 108024 |
| 13 | 275184 |
| 14 | 728784 |
| 15 | 1895760 |
| 16 | 4998528 |
| 17 | 13033560 |
| 18 | 34250904 |
| 19 | 89602632 |
| 20 | 235157640 |
| 21 | 615871032 |