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 | -12 |
| 3 | 124 |
| 4 | -1560 |
| 5 | 21776 |
| 6 | -324256 |
| 7 | 5046096 |
| 8 | -81086112 |
| 9 | 1335113408 |
| 10 | -22408067200 |
| 11 | 381942129792 |
| 12 | -6593494698752 |
| 13 | 115044039049728 |
| 14 | -2025580621035520 |
| 15 | 35943759448886528 |
| 16 | -642162301086308864 |
| 17 | 11541259115333684224 |
| 18 | -208521418711421405184 |