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 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 15 |
| 7 | 31 |
| 8 | 119 |
| 9 | 555 |
| 10 | 2138 |
| 11 | 9548 |
| 12 | 33391 |
| 13 | 136682 |
| 14 | 468971 |
| 15 | 1753525 |
| 16 | 5789709 |
| 17 | 19745186 |
| 18 | 63565260 |
| 19 | 203046061 |
| 20 | 638284176 |
| 21 | 1947963410 |
| 22 | 5979604119 |
| 23 | 17725544038 |
| 24 | 53252284414 |
| 25 | 155128241215 |
| 26 | 456635560332 |
| 27 | 1314718658955 |
| 28 | 3796821176997 |