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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 32640 |
| 5 | 13638780 |
| 6 | 1034019840 |
| 7 | 29699591250 |
| 8 | 460772395776 |
| 9 | 4674233282040 |
| 10 | 34753231503360 |
| 11 | 203842711924830 |
| 12 | 991765602960000 |
| 13 | 4148317444266996 |
| 14 | 15316041761879040 |
| 15 | 50925154505624490 |
| 16 | 154877550296286720 |
| 17 | 436185098521110000 |
| 18 | 1148935457273020416 |