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 | 15 |
| 5 | 222 |
| 6 | 3680 |
| 7 | 69345 |
| 8 | 1477182 |
| 9 | 35234220 |
| 10 | 932070708 |
| 11 | 27109785510 |
| 12 | 860394764515 |
| 13 | 29600058300780 |
| 14 | 1097511032533500 |
| 15 | 43637308561557074 |
| 16 | 1852311640075120980 |
| 17 | 83612841417061582320 |
| 18 | 3999611090385007608840 |
| 19 | 202111299843794061251580 |
| 20 | 10758947714752854861908379 |