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) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 22 |
| 5 | 96 |
| 6 | 718 |
| 7 | 5038 |
| 8 | 38544 |
| 9 | 329780 |
| 10 | 3503640 |
| 11 | 33166848 |
| 12 | 479001598 |
| 13 | 6223425864 |
| 14 | 87178291198 |
| 15 | 1168577230080 |
| 16 | 20915909651520 |
| 17 | 332351050332096 |
| 18 | 6293831116536216 |
| 19 | 121458761380686016 |
| 20 | 2432882508925834560 |
| 21 | 48311155748401677120 |
| 22 | 1113688776127971818016 |