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 | 2 |
| 2 | 12 |
| 3 | 120 |
| 4 | 1320 |
| 5 | 17856 |
| 6 | 273056 |
| 7 | 4772624 |
| 8 | 92626944 |
| 9 | 1986317024 |
| 10 | 46556867456 |
| 11 | 1184827221584 |
| 12 | 32524270418432 |
| 13 | 958020105786536 |