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 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 49 |
| 6 | 233 |
| 7 | 1240 |
| 8 | 7201 |
| 9 | 45521 |
| 10 | 311225 |
| 11 | 2285116 |
| 12 | 17909309 |
| 13 | 149080865 |
| 14 | 1312597361 |
| 15 | 12180044528 |
| 16 | 118740086369 |
| 17 | 1212695223137 |
| 18 | 12942512039697 |
| 19 | 144018843991220 |
| 20 | 1667526171728525 |
| 21 | 20053044685823697 |
| 22 | 250043383489271193 |