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 | 9 |
| 3 | 56 |
| 4 | 286 |
| 5 | 1302 |
| 6 | 5486 |
| 7 | 21897 |
| 8 | 84003 |
| 9 | 312864 |
| 10 | 1139408 |
| 11 | 4079404 |
| 12 | 14417732 |
| 13 | 50465519 |
| 14 | 175400683 |
| 15 | 606660198 |
| 16 | 2091805472 |
| 17 | 7201476498 |
| 18 | 24786314450 |
| 19 | 85384391951 |
| 20 | 294672813537 |
| 21 | 1019666296658 |
| 22 | 3540327824374 |
| 23 | 12341347668900 |