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 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 75 |
| 5 | 904 |
| 6 | 13255 |
| 7 | 229536 |
| 8 | 4587961 |
| 9 | 103971680 |
| 10 | 2634212961 |
| 11 | 73787255200 |
| 12 | 2264440519891 |
| 13 | 75563445303072 |
| 14 | 2724356214102055 |
| 15 | 105546202276277504 |
| 16 | 4373078169296869425 |
| 17 | 192970687573630633216 |
| 18 | 9035613818754820178689 |
| 19 | 447469496697658409400960 |