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 | 0 |
| 3 | 0 |
| 4 | 249849 |
| 5 | 18106704 |
| 6 | 462962955 |
| 7 | 4397342400 |
| 8 | 16602715899 |
| 9 | 25756721120 |
| 10 | 16602715899 |
| 11 | 4397342400 |
| 12 | 462962955 |
| 13 | 18106704 |
| 14 | 249849 |
| 15 | 0 |
| 16 | 0 |
| 17 | 0 |
| 18 | 1 |