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 | 4 |
| 3 | 20 |
| 4 | 108 |
| 5 | 600 |
| 6 | 3368 |
| 7 | 18968 |
| 8 | 106906 |
| 9 | 602532 |
| 10 | 3395402 |
| 11 | 19131460 |
| 12 | 107788900 |
| 13 | 607274848 |