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 | 0 |
| 2 | 81 |
| 3 | 243 |
| 4 | 567 |
| 5 | 1215 |
| 6 | 2511 |
| 7 | 5103 |
| 8 | 10287 |
| 9 | 20655 |
| 10 | 41391 |
| 11 | 82863 |
| 12 | 165807 |
| 13 | 331695 |
| 14 | 663471 |
| 15 | 1327023 |
| 16 | 2654127 |
| 17 | 5308335 |
| 18 | 10616751 |
| 19 | 21233583 |
| 20 | 42467247 |
| 21 | 84934575 |
| 22 | 169869231 |
| 23 | 339738543 |
| 24 | 679477167 |
| 25 | 1358954415 |
| 26 | 2717908911 |
| 27 | 5435817903 |
| 28 | 10871635887 |
| 29 | 21743271855 |
| 30 | 43486543791 |