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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 25 |
| 6 | 89 |
| 7 | 301 |
| 8 | 960 |
| 9 | 3024 |
| 10 | 9305 |
| 11 | 28501 |
| 12 | 86430 |
| 13 | 261625 |
| 14 | 788669 |
| 15 | 2375075 |
| 16 | 7140720 |
| 17 | 21457825 |
| 18 | 64435896 |
| 19 | 193448101 |
| 20 | 580597110 |
| 21 | 1742343323 |
| 22 | 5228050949 |
| 23 | 15686335501 |
| 24 | 47063113320 |
| 25 | 141197991000 |
| 26 | 423610488665 |
| 27 | 1270865802276 |
| 28 | 3812663735790 |
| 29 | 11438127792025 |
| 30 | 34314649427035 |