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 | 0 |
| 2 | -2 |
| 3 | -3 |
| 4 | 6 |
| 5 | 25 |
| 6 | 1 |
| 7 | -147 |
| 8 | -218 |
| 9 | 591 |
| 10 | 2223 |
| 11 | -484 |
| 12 | -14871 |
| 13 | -18759 |
| 14 | 68353 |
| 15 | 222697 |
| 16 | -116058 |
| 17 | -1629671 |
| 18 | -1656989 |
| 19 | 8275203 |
| 20 | 23266031 |
| 21 | -20154144 |
| 22 | -184550412 |
| 23 | -141418628 |
| 24 | 1019061001 |
| 25 | 2468408775 |
| 26 | -3122976521 |
| 27 | -21213927840 |
| 28 | -10837119735 |
| 29 | 126256071125 |
| 30 | 262294667301 |
| 31 | -456407675223 |