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 | 28 |
| 4 | 160 |
| 5 | 976 |
| 6 | 5824 |
| 7 | 35008 |
| 8 | 209920 |
| 9 | 1259776 |
| 10 | 7558144 |
| 11 | 45349888 |
| 12 | 272097280 |
| 13 | 1632587776 |
| 14 | 9795518464 |
| 15 | 58773127168 |
| 16 | 352638730240 |
| 17 | 2115832446976 |
| 18 | 12694994550784 |
| 19 | 76169967566848 |
| 20 | 457019804876800 |
| 21 | 2742118830309376 |
| 22 | 16452712979759104 |