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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 9 |
| 4 | 16 |
| 5 | 400 |
| 6 | 900 |
| 7 | 44100 |
| 8 | 112896 |
| 9 | 9144576 |
| 10 | 25401600 |
| 11 | 3073593600 |
| 12 | 9032601600 |
| 13 | 1526509670400 |
| 14 | 4674935865600 |
| 15 | 1051860569760000 |
| 16 | 3324398837760000 |
| 17 | 960751264112640000 |
| 18 | 3112834095724953600 |
| 19 | 1123733108556708249600 |
| 20 | 3714820193575895040000 |