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 | 32 |
| 5 | 351 |
| 6 | 5057 |
| 7 | 90756 |
| 8 | 1956971 |
| 9 | 49366904 |
| 10 | 1427680932 |
| 11 | 46590895869 |
| 12 | 1694163054597 |
| 13 | 67938488277050 |
| 14 | 2978980898086377 |
| 15 | 141801848209013050 |
| 16 | 7282651452378019772 |
| 17 | 401410357608479625207 |
| 18 | 23635996827115264290005 |