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 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 64 |
| 5 | 832 |
| 6 | 15104 |
| 7 | 352256 |
| 8 | 10037248 |
| 9 | 337936384 |
| 10 | 13126565888 |
| 11 | 577818263552 |
| 12 | 28425821618176 |
| 13 | 1545553369366528 |
| 14 | 92034646352592896 |
| 15 | 5956917762776367104 |
| 16 | 416397789920380321792 |
| 17 | 31262503202358260924416 |
| 18 | 2508985620606225641111552 |
| 19 | 214348807882902869374926848 |
| 20 | 19422044917978876510600167424 |