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 | 1 |
| 2 | -5 |
| 3 | 78 |
| 4 | -1200 |
| 5 | 19680 |
| 6 | -351360 |
| 7 | 6854400 |
| 8 | -145797120 |
| 9 | 3367526400 |
| 10 | -84072038400 |
| 11 | 2258332876800 |
| 12 | -64990937088000 |
| 13 | 1995834890649600 |
| 14 | -65167516237824000 |
| 15 | 2254974602969088000 |
| 16 | -82443156980760576000 |
| 17 | 3176032637949050880000 |
| 18 | -128603097714237898752000 |
| 19 | 5460911310769351557120000 |