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 | 4 |
| 2 | 15 |
| 3 | 55 |
| 4 | 199 |
| 5 | 714 |
| 6 | 2547 |
| 7 | 9048 |
| 8 | 32043 |
| 9 | 113212 |
| 10 | 399265 |
| 11 | 1406079 |
| 12 | 4946137 |
| 13 | 17383162 |
| 14 | 61048359 |
| 15 | 214270215 |
| 16 | 751691811 |
| 17 | 2636004228 |
| 18 | 9240836733 |
| 19 | 32386215981 |
| 20 | 113478349989 |
| 21 | 397544907486 |
| 22 | 1392493797765 |
| 23 | 4876916883090 |
| 24 | 17078574481941 |
| 25 | 59802541979964 |