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 | 0 |
| 3 | 0 |
| 4 | -6 |
| 5 | -30 |
| 6 | 0 |
| 7 | 420 |
| 8 | 2100 |
| 9 | 6804 |
| 10 | -20160 |
| 11 | -376200 |
| 12 | -2102760 |
| 13 | -6606600 |
| 14 | 53237184 |
| 15 | 965306160 |
| 16 | 5941244400 |
| 17 | 12774059760 |
| 18 | -305998041600 |
| 19 | -5264368533216 |
| 20 | -33983490935520 |
| 21 | -16008359119200 |
| 22 | 3139364813249280 |
| 23 | 52132631033313600 |
| 24 | 341037535726730304 |
| 25 | -715693892444414400 |