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 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 12 |
| 6 | 39 |
| 7 | 138 |
| 8 | 503 |
| 9 | 1864 |
| 10 | 6936 |
| 11 | 25868 |
| 12 | 96512 |
| 13 | 360203 |
| 14 | 1344408 |
| 15 | 5018051 |
| 16 | 18729944 |
| 17 | 69910398 |
| 18 | 260943079 |
| 19 | 973980990 |
| 20 | 3635421345 |
| 21 | 13569354266 |
| 22 | 50648137765 |
| 23 | 189046143161 |