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 | 2 |
| 2 | 4 |
| 3 | 10 |
| 4 | 70 |
| 5 | 430 |
| 6 | 4090 |
| 7 | 86530 |
| 8 | 513100 |
| 9 | 913570 |
| 10 | 7914340 |
| 11 | 6593621380 |
| 12 | 9366241600 |