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 | 126 |
| 2 | 9576 |
| 3 | 571536 |
| 4 | 29583792 |
| 5 | 1395690912 |
| 6 | 61756307712 |
| 7 | 2609370796032 |
| 8 | 106548747072768 |
| 9 | 4239618914539008 |
| 10 | 165370550603102208 |
| 11 | 6351034526066700288 |
| 12 | 240942052882092847104 |
| 13 | 9052126728954680254464 |