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 | 3 |
| 2 | 4 |
| 3 | 6 |
| 4 | 12 |
| 5 | 20 |
| 6 | 24 |
| 7 | 70 |
| 8 | 714 |
| 9 | 1364 |
| 10 | 2706 |
| 11 | 26220 |
| 12 | 53570 |
| 13 | 67044 |
| 14 | 164220 |
| 15 | 5053620 |
| 16 | 60369855 |
| 17 | 191895456 |
| 18 | 475528443 |
| 19 | 715236599 |