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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 40320 |
| 9 | 362880 |
| 10 | 3628800 |
| 11 | 3628789 |
| 12 | 3628668 |
| 13 | 3627084 |
| 14 | 3604776 |
| 15 | 3268440 |
| 16 | -2136960 |
| 17 | -94389120 |
| 18 | -1760693760 |
| 19 | -33518499840 |
| 20 | -670438944000 |
| 21 | -670438943979 |
| 22 | -670438943538 |
| 23 | -670438933374 |
| 24 | -670438688976 |
| 25 | -670432568400 |
| 26 | -670273178400 |