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 | 4 |
| 4 | 25 |
| 5 | 271 |
| 6 | 5682 |
| 7 | 237684 |
| 8 | 20042357 |
| 9 | 3404651985 |
| 10 | 1162523674892 |
| 11 | 796395726736678 |
| 12 | 1093229314594543016 |
| 13 | 3004753338859186373234 |
| 14 | 16527845763725396055765240 |
| 15 | 181891586856152393087373330332 |
| 16 | 4004313490358484085907684748704180 |
| 17 | 176328671349936542115174881107633828418 |