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) |
|---|---|
| 3 | 1 |
| 4 | 20 |
| 5 | 300 |
| 6 | 4060 |
| 7 | 52360 |
| 8 | 658008 |
| 9 | 8145060 |
| 10 | 99884400 |
| 11 | 1217566350 |
| 12 | 14783142660 |
| 13 | 179013799328 |
| 14 | 2163842859360 |
| 15 | 26123889412400 |
| 16 | 315136287090800 |
| 17 | 3799541229226200 |
| 18 | 45795673964460816 |
| 19 | 551876736990451095 |