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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 42 |
| 6 | 138 |
| 7 | 466 |
| 8 | 1643 |
| 9 | 5919 |
| 10 | 21773 |
| 11 | 81279 |
| 12 | 307483 |
| 13 | 1175352 |
| 14 | 4534161 |
| 15 | 17626999 |
| 16 | 68992703 |
| 17 | 271641249 |
| 18 | 1075144364 |
| 19 | 4275274867 |
| 20 | 17071822275 |
| 21 | 68428152475 |
| 22 | 275217386092 |
| 23 | 1110375948303 |
| 24 | 4492641333003 |
| 25 | 18225081419544 |
| 26 | 74111194585752 |
| 27 | 302040709982249 |