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 | 4 |
| 4 | -19 |
| 5 | -64 |
| 6 | 1207 |
| 7 | 5440 |
| 8 | -164071 |
| 9 | -954368 |
| 10 | 39943691 |
| 11 | 284754944 |
| 12 | -15250391099 |
| 13 | -128749666304 |
| 14 | 8402599565375 |
| 15 | 81978198409216 |
| 16 | -6309988001033167 |
| 17 | -69853770233675776 |
| 18 | 6194681665486634899 |
| 19 | 76717804389440684032 |