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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 33 |
| 5 | 97 |
| 6 | 288 |
| 7 | 855 |
| 8 | 2544 |
| 9 | 7577 |
| 10 | 22590 |
| 11 | 67399 |
| 12 | 201215 |
| 13 | 601017 |
| 14 | 1795966 |
| 15 | 5368659 |
| 16 | 16053417 |
| 17 | 48015873 |
| 18 | 143649102 |
| 19 | 429842511 |
| 20 | 1286452725 |
| 21 | 3850770081 |
| 22 | 11528245602 |
| 23 | 34517105907 |
| 24 | 103360732956 |
| 25 | 309543786441 |
| 26 | 927106804368 |
| 27 | 2776994293355 |