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 | 5 |
| 4 | 81 |
| 5 | 29 |
| 6 | -4623 |
| 7 | -20035 |
| 8 | 415041 |
| 9 | 4838909 |
| 10 | -46093743 |
| 11 | -1309934275 |
| 12 | 3230184801 |
| 13 | 419574363389 |
| 14 | 2065056788337 |
| 15 | -154120122603715 |
| 16 | -2307971235744639 |
| 17 | 59954627542249469 |
| 18 | 1959892188447337617 |
| 19 | -19474957767402204355 |
| 20 | -1658215397958862557279 |