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 | -6 |
| 3 | 37 |
| 4 | 186 |
| 5 | -961 |
| 6 | -14166 |
| 7 | 410189 |
| 8 | 2009946 |
| 9 | -18708871 |
| 10 | -458225526 |
| 11 | 10426234927 |
| 12 | 153212718906 |
| 13 | -2059985998981 |
| 14 | -70632832168086 |
| 15 | 8766253488312013 |
| 16 | 42939614599671066 |
| 17 | -754976143412185291 |
| 18 | -33282798350926545846 |
| 19 | 1308065815531646653417 |