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 | 1026 |
| 3 | 88578 |
| 4 | 2097160 |
| 5 | 24414075 |
| 6 | 181398546 |
| 7 | 988663396 |
| 8 | 4294967328 |
| 9 | 15690529845 |
| 10 | 50000000050 |
| 11 | 142655835366 |
| 12 | 371504185416 |
| 13 | 896080197103 |
| 14 | 2024782584930 |
| 15 | 4324877929800 |
| 16 | 8796093022336 |
| 17 | 17135948153961 |
| 18 | 32134205039778 |
| 19 | 58245129449290 |
| 20 | 102400000000200 |