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 | 4 |
| 3 | 27 |
| 4 | 220 |
| 5 | 2265 |
| 6 | 27246 |
| 7 | 393421 |
| 8 | 6548536 |
| 9 | 126257697 |
| 10 | 2767122010 |
| 11 | 68387691141 |
| 12 | 1882488882660 |
| 13 | 57198150690577 |
| 14 | 1900138953826582 |
| 15 | 68502961685976525 |
| 16 | 2662089147552365296 |
| 17 | 110887849449189768513 |
| 18 | 4926985461324765096498 |
| 19 | 232544882903837769171829 |