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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 17 |
| 5 | 52 |
| 6 | 156 |
| 7 | 468 |
| 8 | 1405 |
| 9 | 4217 |
| 10 | 12653 |
| 11 | 37960 |
| 12 | 113880 |
| 13 | 341640 |
| 14 | 1024921 |
| 15 | 3074765 |
| 16 | 9224297 |
| 17 | 27672892 |
| 18 | 83018676 |
| 19 | 249056028 |
| 20 | 747168085 |
| 21 | 2241504257 |
| 22 | 6724512773 |
| 23 | 20173538320 |
| 24 | 60520614960 |
| 25 | 181561844880 |