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 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 6 |
| 5 | 0 |
| 6 | 120 |
| 7 | 0 |
| 8 | 5250 |
| 9 | 0 |
| 10 | 395010 |
| 11 | 0 |
| 12 | 45197460 |
| 13 | 0 |
| 14 | 7299452160 |
| 15 | 0 |
| 16 | 1580682203100 |
| 17 | 0 |
| 18 | 441926274289500 |
| 19 | 0 |
| 20 | 154940341854097800 |
| 21 | 0 |
| 22 | 66565404923242024800 |
| 23 | 0 |
| 24 | 34389901168124209507800 |
| 25 | 0 |
| 26 | 21034386936107260971255000 |
| 27 | 0 |
| 28 | 15032296693671903309613950000 |
| 29 | 0 |
| 30 | 12411582569784462888618434640000 |
| 31 | 0 |