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 | 3 |
| 2 | 15 |
| 3 | 93 |
| 4 | 621 |
| 5 | 4425 |
| 6 | 32703 |
| 7 | 248901 |
| 8 | 1934007 |
| 9 | 15285771 |
| 10 | 122437215 |
| 11 | 991731999 |
| 12 | 8107830597 |