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 | 4 |
| 1 | 12 |
| 2 | 72 |
| 3 | 2111 |
| 4 | 14265 |
| 5 | 70424 |
| 6 | 308832 |
| 7 | 4371476 |
| 8 | 320218450 |
| 9 | 1101000257 |
| 10 | 14020589841 |
| 11 | 102772320834 |
| 12 | 963205851651 |
| 13 | 5997003656523 |
| 14 | 50649135127796 |
| 15 | 640772902021920 |
| 16 | 2101002284323870 |
| 17 | 35029677728070645 |
| 18 | 176996397541889098 |
| 19 | 1433436623499128186 |