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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1736 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 6107895 |
| 10 | 458738443 |
| 11 | 0 |
| 12 | 117093979072 |
| 13 | 856605019673 |
| 14 | 5774401272921 |
| 15 | 96699253829728 |
| 16 | 5810550306096509 |
| 17 | 450529175803834166 |
| 18 | 0 |
| 19 | 44350645312365507266 |
| 20 | 271761692158955752596 |
| 21 | 2941647823169311845731 |