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 | 5 |
| 4 | 14 |
| 5 | 54 |
| 6 | 264 |
| 7 | 1560 |
| 8 | 10920 |
| 9 | 97440 |
| 10 | 876960 |
| 11 | 10263240 |
| 12 | 112895640 |
| 13 | 1348827480 |
| 14 | 18029171160 |
| 15 | 264370186080 |
| 16 | 3806158356000 |
| 17 | 62703141621120 |
| 18 | 1128159304272000 |
| 19 | 20422064875212000 |
| 20 | 404757215566704000 |
| 21 | 8208550091549808000 |
| 22 | 177650747421074928000 |