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) |
|---|---|
| 4 | 1 |
| 5 | 7 |
| 6 | 33 |
| 7 | 133 |
| 8 | 496 |
| 9 | 1770 |
| 10 | 6142 |
| 11 | 20902 |
| 12 | 70107 |
| 13 | 232489 |
| 14 | 763927 |
| 15 | 2491107 |
| 16 | 8071234 |
| 17 | 26007364 |
| 18 | 83402988 |
| 19 | 266351548 |
| 20 | 847482277 |
| 21 | 2687729595 |
| 22 | 8499036925 |
| 23 | 26804655025 |
| 24 | 84336597636 |
| 25 | 264777690382 |
| 26 | 829636763338 |
| 27 | 2594821366338 |
| 28 | 8102197327711 |
| 29 | 25259791668925 |
| 30 | 78638974063827 |