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 | 2 |
| 2 | 12 |
| 3 | 120 |
| 4 | 1607 |
| 5 | 26862 |
| 6 | 536816 |
| 7 | 12466468 |
| 8 | 329648274 |
| 9 | 9774030812 |
| 10 | 321057111308 |
| 11 | 11570735358300 |
| 12 | 453874209520951 |
| 13 | 19248243764760562 |
| 14 | 877497573254643438 |
| 15 | 42791783608096161848 |
| 16 | 2222646606788322292656 |
| 17 | 122500263059540271947448 |
| 18 | 7140154262067048381368062 |
| 19 | 438819217371889984410077532 |
| 20 | 28360033818941846664929891481 |
| 21 | 1922734355204851243123303962324 |