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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 552 |
| 7 | 2826 |
| 8 | 17080 |
| 9 | 117816 |
| 10 | 943250 |
| 11 | 8330356 |
| 12 | 82954582 |
| 13 | 915854808 |
| 14 | 11147075946 |
| 15 | 147948526182 |