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 | 2 |
| 1 | 4 |
| 2 | 12 |
| 3 | 36 |
| 4 | 118 |
| 5 | 392 |
| 6 | 1336 |
| 7 | 4642 |
| 8 | 16458 |
| 9 | 59025 |
| 10 | 213922 |
| 11 | 781924 |
| 12 | 2879938 |
| 13 | 10673034 |
| 14 | 39769185 |
| 15 | 148880193 |
| 16 | 559658890 |
| 17 | 2111459404 |
| 18 | 7991867657 |
| 19 | 30336822624 |
| 20 | 115457945437 |
| 21 | 440455347499 |
| 22 | 1683882372217 |
| 23 | 6450190109521 |
| 24 | 24752190739937 |
| 25 | 95142124007068 |
| 26 | 366264701294309 |
| 27 | 1411989176124066 |