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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 30 |
| 5 | 60 |
| 6 | 244230 |
| 7 | 6930 |
| 8 | 546840 |
| 9 | 3120613860 |
| 10 | 7399357350 |
| 11 | 10719893274090 |
| 12 | 173761834256010 |
| 13 | 14772517344885300 |