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 | 1 |
| 2 | 5 |
| 3 | 25 |
| 4 | 121 |
| 5 | 589 |
| 6 | 2821 |
| 7 | 13565 |
| 8 | 64661 |
| 9 | 308981 |
| 10 | 1468313 |
| 11 | 6989025 |
| 12 | 33140457 |
| 13 | 157329085 |
| 14 | 744818613 |
| 15 | 3529191009 |
| 16 | 16686979329 |
| 17 | 78955042017 |
| 18 | 372953947349 |
| 19 | 1762672203269 |
| 20 | 8319554639789 |
| 21 | 39285015083693 |
| 22 | 185296997240401 |
| 23 | 874331369198569 |