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 | 9 |
| 2 | 49 |
| 3 | 209 |
| 4 | 769 |
| 5 | 2561 |
| 6 | 7937 |
| 7 | 23297 |
| 8 | 65537 |
| 9 | 178177 |
| 10 | 471041 |
| 11 | 1216513 |
| 12 | 3080193 |
| 13 | 7667713 |
| 14 | 18808833 |
| 15 | 45547521 |
| 16 | 109051905 |
| 17 | 258473985 |
| 18 | 607125505 |
| 19 | 1414529025 |
| 20 | 3271557121 |
| 21 | 7516192769 |
| 22 | 17163091969 |