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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 1 |
| 4 | 1 |
| 5 | -2 |
| 6 | 1 |
| 7 | -2 |
| 8 | 5 |
| 9 | -4 |
| 10 | 1 |
| 11 | 12 |
| 12 | -32 |
| 13 | 29 |
| 14 | -10 |
| 15 | 1 |
| 16 | -288 |
| 17 | 780 |
| 18 | -728 |
| 19 | 269 |
| 20 | -34 |
| 21 | 1 |
| 22 | 34560 |
| 23 | -93888 |
| 24 | 88140 |
| 25 | -33008 |
| 26 | 4349 |
| 27 | -154 |
| 28 | 1 |
| 29 | -24883200 |
| 30 | 67633920 |
| 31 | -63554688 |
| 32 | 23853900 |
| 33 | -3164288 |
| 34 | 115229 |
| 35 | -874 |
| 36 | 1 |
| 37 | 125411328000 |
| 38 | -340899840000 |
| 39 | 320383261440 |
| 40 | -120287210688 |
| 41 | 15971865420 |
| 42 | -583918448 |
| 43 | 4520189 |