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 | 3 |
| 1 | 12 |
| 2 | 30 |
| 3 | 66 |
| 4 | 138 |
| 5 | 282 |
| 6 | 570 |
| 7 | 1146 |
| 8 | 2298 |
| 9 | 4602 |
| 10 | 9210 |
| 11 | 18426 |
| 12 | 36858 |
| 13 | 73722 |
| 14 | 147450 |
| 15 | 294906 |
| 16 | 589818 |
| 17 | 1179642 |
| 18 | 2359290 |
| 19 | 4718586 |
| 20 | 9437178 |
| 21 | 18874362 |
| 22 | 37748730 |
| 23 | 75497466 |
| 24 | 150994938 |
| 25 | 301989882 |
| 26 | 603979770 |
| 27 | 1207959546 |
| 28 | 2415919098 |
| 29 | 4831838202 |
| 30 | 9663676410 |
| 31 | 19327352826 |