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 | 2 |
| 4 | 9 |
| 5 | 30 |
| 6 | 91 |
| 7 | 258 |
| 8 | 729 |
| 9 | 2018 |
| 10 | 5613 |
| 11 | 15546 |
| 12 | 43315 |
| 13 | 120750 |
| 14 | 338259 |
| 15 | 950062 |
| 16 | 2678499 |
| 17 | 7573350 |
| 18 | 21480739 |
| 19 | 61088874 |
| 20 | 174184755 |
| 21 | 497812638 |
| 22 | 1425847623 |
| 23 | 4092087522 |
| 24 | 11765822365 |
| 25 | 33887517870 |
| 26 | 97756387365 |
| 27 | 282414624746 |
| 28 | 816999710223 |
| 29 | 2366509198350 |
| 30 | 6862930841141 |