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 | 0 |
| 1 | 1 |
| 2 | 20 |
| 3 | 380 |
| 4 | 7200 |
| 5 | 136400 |
| 6 | 2584000 |
| 7 | 48952000 |
| 8 | 927360000 |
| 9 | 17568160000 |
| 10 | 332816000000 |
| 11 | 6304956800000 |
| 12 | 119442816000000 |
| 13 | 2262757184000000 |
| 14 | 42866287360000000 |
| 15 | 812070603520000000 |
| 16 | 15384086323200000000 |