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 | 3 |
| 5 | 40 |
| 6 | 745 |
| 7 | 21028 |
| 8 | 973889 |
| 9 | 80133088 |
| 10 | 12523299729 |
| 11 | 3847333778244 |
| 12 | 2341705361100633 |
| 13 | 2821794389863015840 |
| 14 | 6728707109106848947081 |
| 15 | 31769173063866390661714996 |
| 16 | 297278309767391164611330317921 |