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 | 5 |
| 3 | 17 |
| 4 | 80 |
| 5 | 365 |
| 6 | 1981 |
| 7 | 11222 |
| 8 | 69511 |
| 9 | 455663 |
| 10 | 3169244 |
| 11 | 23170347 |
| 12 | 177513359 |
| 13 | 1418920570 |
| 14 | 11798710013 |
| 15 | 101778754655 |
| 16 | 908722427531 |
| 17 | 8380602471646 |
| 18 | 79692654473866 |
| 19 | 780142956502644 |
| 20 | 7851084073063731 |
| 21 | 81120767066417308 |