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 | 5 |
| 2 | 28 |
| 3 | 164 |
| 4 | 976 |
| 5 | 5840 |
| 6 | 35008 |
| 7 | 209984 |
| 8 | 1259776 |
| 9 | 7558400 |
| 10 | 45349888 |
| 11 | 272098304 |
| 12 | 1632587776 |
| 13 | 9795522560 |
| 14 | 58773127168 |
| 15 | 352638746624 |
| 16 | 2115832446976 |
| 17 | 12694994616320 |
| 18 | 76169967566848 |
| 19 | 457019805138944 |
| 20 | 2742118830309376 |