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 | 0 |
| 2 | 15 |
| 3 | 105 |
| 4 | 2016 |
| 5 | 11628 |
| 6 | 203203 |
| 7 | 1152921 |
| 8 | 19968040 |
| 9 | 113108320 |
| 10 | 1957220895 |
| 11 | 11084786065 |
| 12 | 191793185496 |
| 13 | 1086209028828 |
| 14 | 18793829460003 |
| 15 | 106437529743441 |
| 16 | 1841604033412080 |
| 17 | 10429792989769440 |
| 18 | 180458406785594575 |
| 19 | 1022013288177368025 |
| 20 | 17683082313822046576 |