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 | -2 |
| 2 | -6 |
| 3 | -48 |
| 4 | -720 |
| 5 | -17280 |
| 6 | -604800 |
| 7 | -29030400 |
| 8 | -1828915200 |
| 9 | -146313216000 |
| 10 | -14485008384000 |
| 11 | -1738201006080000 |
| 12 | -248562743869440000 |
| 13 | -41758540970065920000 |
| 14 | -8142915489162854400000 |
| 15 | -1824013069572479385600000 |
| 16 | -465123332740982243328000000 |