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 | 9 |
| 3 | 0 |
| 4 | 12070 |
| 5 | 0 |
| 6 | 126447741 |
| 7 | 0 |
| 8 | 5100496997940 |
| 9 | 0 |
| 10 | 562605048135059545 |
| 11 | 0 |
| 12 | 138523311740417986721274 |
| 13 | 0 |
| 14 | 66543520389763227261554370645 |
| 15 | 0 |
| 16 | 56664734898911130799849838608991176 |
| 17 | 0 |
| 18 | 79610326854782816434044397510470501877041 |