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 | -3 |
| 3 | -21 |
| 4 | 27 |
| 5 | 927 |
| 6 | 387 |
| 7 | -78111 |
| 8 | -211167 |
| 9 | 10887129 |
| 10 | 61228629 |
| 11 | -2278564101 |
| 12 | -20995423317 |
| 13 | 669639978711 |
| 14 | 9055735268283 |
| 15 | -263207953694367 |
| 16 | -4900375484030367 |
| 17 | 133357760824723281 |
| 18 | 3278778524907635277 |
| 19 | -84617763517115570709 |
| 20 | -2669012118280627019109 |