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 | -2 |
| 4 | 21 |
| 5 | -4 |
| 6 | -150 |
| 7 | 155 |
| 8 | 1029 |
| 9 | -2072 |
| 10 | -6468 |
| 11 | 22056 |
| 12 | 34122 |
| 13 | -208857 |
| 14 | -106249 |
| 15 | 1816958 |
| 16 | -639067 |
| 17 | -14629264 |
| 18 | 17635800 |
| 19 | 108117620 |
| 20 | -239571684 |
| 21 | -711876496 |
| 22 | 2628772968 |
| 23 | 3825823888 |
| 24 | -25582846134 |
| 25 | -10997156129 |
| 26 | 227594431035 |
| 27 | -98360217830 |
| 28 | -1864646227185 |