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 | 1 |
| 4 | 12 |
| 5 | 105 |
| 6 | 816 |
| 7 | 5985 |
| 8 | 42504 |
| 9 | 296010 |
| 10 | 2035800 |
| 11 | 13884156 |
| 12 | 94143280 |
| 13 | 635745396 |
| 14 | 4280561376 |
| 15 | 28760021745 |
| 16 | 192928249296 |
| 17 | 1292706174900 |
| 18 | 8654327655120 |
| 19 | 57902201338905 |
| 20 | 387221678682300 |
| 21 | 2588713818544245 |