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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 12 |
| 6 | 48 |
| 7 | 192 |
| 8 | 768 |
| 9 | 3840 |
| 10 | 23040 |
| 11 | 161280 |
| 12 | 1128960 |
| 13 | 9031680 |
| 14 | 72253440 |
| 15 | 578027520 |
| 16 | 4624220160 |
| 17 | 41617981440 |
| 18 | 416179814400 |
| 19 | 4577977958400 |
| 20 | 54935735500800 |
| 21 | 659228826009600 |
| 22 | 8569974738124800 |
| 23 | 119979646333747200 |
| 24 | 1679715048672460800 |
| 25 | 25195725730086912000 |
| 26 | 377935885951303680000 |