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 | -4 |
| 2 | -24 |
| 3 | -1248 |
| 4 | 1632 |
| 5 | -267136 |
| 6 | -669440 |
| 7 | -56925184 |
| 8 | 597165568 |
| 9 | -19934894080 |
| 10 | 61831327744 |
| 11 | -3209599664128 |
| 12 | 47593545383936 |
| 13 | -840449808072704 |
| 14 | 8113679782510592 |
| 15 | -350055154021040128 |
| 16 | 5703847053344768000 |
| 17 | -57129722970675609600 |
| 18 | 704939718429511778304 |