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) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 8 |
| 4 | 58 |
| 5 | 492 |
| 6 | 5074 |
| 7 | 60888 |
| 8 | 835482 |
| 9 | 12895796 |
| 10 | 221169970 |
| 11 | 4172486496 |
| 12 | 85872215290 |
| 13 | 1914575169756 |
| 14 | 45970251182418 |
| 15 | 1182618181384424 |
| 16 | 32451961380002458 |
| 17 | 946163712877067460 |
| 18 | 29208900504551394610 |
| 19 | 951798961321369842864 |
| 20 | 32647628386008050898810 |