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 | -11 |
| 2 | 157 |
| 3 | -99 |
| 4 | 7319 |
| 5 | -165 |
| 6 | 4171 |
| 7 | -23991 |
| 8 | 1512239 |
| 9 | 1852983 |
| 10 | -312831415 |
| 11 | -255444123 |
| 12 | 304328758067 |
| 13 | 49452923091 |
| 14 | -1056622730741 |
| 15 | -12890472052095 |
| 16 | 26749041130401343 |
| 17 | 4351895470184559 |
| 18 | -2270808626732553983 |
| 19 | -1847319496687281507 |
| 20 | 3100305824706838403989 |