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 | 20 |
| 2 | 400 |
| 3 | 432 |
| 4 | 2688 |
| 5 | 11424 |
| 6 | 44064 |
| 7 | 198000 |
| 8 | 844800 |
| 9 | 3542544 |
| 10 | 15213984 |
| 11 | 64859616 |
| 12 | 275633280 |
| 13 | 1175819856 |
| 14 | 5010674496 |
| 15 | 21340192176 |
| 16 | 90942560256 |
| 17 | 387500834976 |
| 18 | 1650940063776 |
| 19 | 7034502996720 |
| 20 | 29972774288640 |
| 21 | 127706156346384 |