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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | -23 |
| 5 | -599 |
| 6 | -8999 |
| 7 | -104999 |
| 8 | -868559 |
| 9 | 5246641 |
| 10 | 582598801 |
| 11 | 21205760401 |
| 12 | 571129277401 |
| 13 | 11475082596121 |
| 14 | 81837031796521 |
| 15 | -7904119577117399 |
| 16 | -596529385424263199 |
| 17 | -28051840646006771999 |
| 18 | -991870986521074646879 |
| 19 | -21837506791918601443679 |