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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 17 |
| 7 | 62 |
| 8 | 259 |
| 9 | 1230 |
| 10 | 6592 |
| 11 | 39313 |
| 12 | 258575 |
| 13 | 1860318 |
| 14 | 14538245 |
| 15 | 122670593 |
| 16 | 1111715644 |
| 17 | 10771412394 |
| 18 | 111125142979 |
| 19 | 1216309735378 |
| 20 | 14078811306851 |
| 21 | 171837279141312 |
| 22 | 2205768169095338 |
| 23 | 29707098687614285 |