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 | 1 |
| 2 | 4 |
| 3 | 36 |
| 4 | 144 |
| 5 | 3600 |
| 6 | 400 |
| 7 | 19600 |
| 8 | 78400 |
| 9 | 6350400 |
| 10 | 6350400 |
| 11 | 768398400 |
| 12 | 768398400 |
| 13 | 129859329600 |
| 14 | 129859329600 |
| 15 | 129859329600 |
| 16 | 519437318400 |
| 17 | 150117385017600 |
| 18 | 16679709446400 |
| 19 | 6021375110150400 |
| 20 | 240855004406016 |
| 21 | 26761667156224 |