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 | 1 |
| 1 | 4 |
| 2 | 14 |
| 3 | 46 |
| 4 | 146 |
| 5 | 454 |
| 6 | 1394 |
| 7 | 4246 |
| 8 | 12866 |
| 9 | 38854 |
| 10 | 117074 |
| 11 | 352246 |
| 12 | 1058786 |
| 13 | 3180454 |
| 14 | 9549554 |
| 15 | 28665046 |
| 16 | 86027906 |
| 17 | 258149254 |
| 18 | 774578834 |
| 19 | 2323998646 |
| 20 | 6972520226 |
| 21 | 20918609254 |
| 22 | 62757924914 |
| 23 | 188277969046 |
| 24 | 564842295746 |
| 25 | 1694543664454 |
| 26 | 5083664547794 |
| 27 | 15251060752246 |