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 | 1 |
| 3 | 0 |
| 4 | -4 |
| 5 | -12 |
| 6 | 4 |
| 7 | 240 |
| 8 | 1184 |
| 9 | -1008 |
| 10 | -59504 |
| 11 | -401280 |
| 12 | 643136 |
| 13 | 38584128 |
| 14 | 323581504 |
| 15 | -848090880 |
| 16 | -51666451456 |
| 17 | -509739310848 |
| 18 | 2004840714496 |
| 19 | 123888658698240 |
| 20 | 1386061762251776 |
| 21 | -7721141999864832 |
| 22 | -483475390212586496 |
| 23 | -5974101514137292800 |
| 24 | 45231727252157947904 |