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 | 4 |
| 3 | 108 |
| 4 | 4448 |
| 5 | 276560 |
| 6 | 24034752 |
| 7 | 2782112704 |
| 8 | 413640580096 |
| 9 | 76768625740032 |
| 10 | 17380983003345920 |
| 11 | 4711153236657376256 |
| 12 | 1505098422997799215104 |
| 13 | 559357234754573189828608 |