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 | 3 |
| 2 | 7 |
| 3 | 19 |
| 4 | 57 |
| 5 | 176 |
| 6 | 557 |
| 7 | 1806 |
| 8 | 5954 |
| 9 | 19897 |
| 10 | 67235 |
| 11 | 229366 |
| 12 | 788688 |
| 13 | 2730810 |
| 14 | 9512107 |
| 15 | 33309444 |
| 16 | 117190184 |
| 17 | 414039578 |
| 18 | 1468349782 |
| 19 | 5225201321 |
| 20 | 18651958885 |
| 21 | 66769742002 |
| 22 | 239643164237 |
| 23 | 862168692562 |
| 24 | 3108716586702 |
| 25 | 11232127258416 |
| 26 | 40660388117380 |
| 27 | 147453014455094 |