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 | 1 |
| 1 | -14 |
| 2 | 112 |
| 3 | -672 |
| 4 | 3346 |
| 5 | -14560 |
| 6 | 57120 |
| 7 | -206208 |
| 8 | 694960 |
| 9 | -2209774 |
| 10 | 6683040 |
| 11 | -19345760 |
| 12 | 53874912 |
| 13 | -144936288 |
| 14 | 377965760 |
| 15 | -958231680 |
| 16 | 2367566866 |
| 17 | -5713057728 |
| 18 | 13488657168 |
| 19 | -31210552800 |
| 20 | 70873262880 |
| 21 | -158145658560 |