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 | -1 |
| 4 | 1 |
| 5 | 1 |
| 6 | -11 |
| 7 | 23 |
| 8 | -20 |
| 9 | 731 |
| 10 | -4860 |
| 11 | -91205 |
| 12 | 138329 |
| 13 | 24813133 |
| 14 | 222203538 |
| 15 | -11857627480 |
| 16 | -340590475934 |
| 17 | 7798573417057 |
| 18 | 602467423292955 |
| 19 | -4252676907049394 |
| 20 | -1469602631093521547 |
| 21 | -14928401886412967891 |
| 22 | 4982240895059491727005 |
| 23 | 167923794808862463264206 |