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 | 3 |
| 2 | -3 |
| 3 | 5 |
| 4 | -45 |
| 5 | 117 |
| 6 | -663 |
| 7 | 1989 |
| 8 | -49725 |
| 9 | 160225 |
| 10 | -1057485 |
| 11 | 3556995 |
| 12 | -48612265 |
| 13 | 168273225 |
| 14 | -1177912575 |
| 15 | 4161957765 |
| 16 | -237231592605 |
| 17 | 851242773465 |
| 18 | -6147864475025 |
| 19 | 22326455198775 |
| 20 | -325966245902115 |
| 21 | 1195209568307755 |
| 22 | -8801088639357105 |
| 23 | 32525762362841475 |
| 24 | -964930950097630425 |