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 | 2 |
| 3 | 17 |
| 4 | 98 |
| 5 | 882 |
| 6 | 7812 |
| 7 | 78129 |
| 8 | 815474 |
| 9 | 8955650 |
| 10 | 101869508 |
| 11 | 1194964498 |
| 12 | 14374530436 |
| 13 | 176681194276 |
| 14 | 2212121332488 |
| 15 | 28145258688369 |
| 16 | 363177582488274 |
| 17 | 4745064935840178 |
| 18 | 62687665026816228 |
| 19 | 836447728509168930 |
| 20 | 11261240896657686660 |
| 21 | 152847558411986548260 |