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 | -1 |
| 3 | -3 |
| 4 | 4 |
| 5 | 12 |
| 6 | -38 |
| 7 | -33 |
| 8 | 428 |
| 9 | -696 |
| 10 | -3640 |
| 11 | 23140 |
| 12 | -24766 |
| 13 | -358024 |
| 14 | 2254416 |
| 15 | -2636188 |
| 16 | -48229769 |
| 17 | 372329934 |
| 18 | -777177980 |
| 19 | -8375653981 |
| 20 | 92394060425 |
| 21 | -351172999190 |
| 22 | -1461026905290 |
| 23 | 30190430840555 |
| 24 | -192411489098224 |
| 25 | 66898238530023 |
| 26 | 11177278011895383 |