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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | -1 |
| 4 | 2 |
| 5 | 3 |
| 6 | 1 |
| 7 | -11 |
| 8 | -16 |
| 9 | 35 |
| 10 | -129 |
| 11 | -299 |
| 12 | -386 |
| 13 | 3977 |
| 14 | 8063 |
| 15 | -42489 |
| 16 | 269344 |
| 17 | 1000009 |
| 18 | 3727745 |
| 19 | -47166649 |
| 20 | -123526014 |
| 21 | 1764203419 |
| 22 | -18228952703 |
| 23 | -113727892147 |
| 24 | -1065812586544 |
| 25 | 18344075481339 |
| 26 | 52130069331199 |
| 27 | -2470319425874195 |