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 | 4 |
| 2 | 12 |
| 3 | 28 |
| 4 | 76 |
| 5 | 204 |
| 6 | 540 |
| 7 | 1404 |
| 8 | 3724 |
| 9 | 9748 |
| 10 | 25772 |
| 11 | 67940 |
| 12 | 179068 |
| 13 | 472580 |
| 14 | 1245620 |
| 15 | 3286308 |
| 16 | 8666956 |
| 17 | 22861604 |
| 18 | 60301764 |
| 19 | 159063748 |
| 20 | 419582396 |
| 21 | 1106796012 |
| 22 | 2919664716 |
| 23 | 7701735292 |
| 24 | 20317148476 |
| 25 | 53595401604 |
| 26 | 141385319932 |
| 27 | 372973583908 |
| 28 | 983913216292 |
| 29 | 2595592842460 |