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 | 0 |
| 4 | -2 |
| 5 | -1 |
| 6 | 7 |
| 7 | 0 |
| 8 | -44 |
| 9 | 69 |
| 10 | 276 |
| 11 | -1471 |
| 12 | 675 |
| 13 | 20407 |
| 14 | -90560 |
| 15 | -20552 |
| 16 | 2141700 |
| 17 | -10558223 |
| 18 | -675239 |
| 19 | 329376824 |
| 20 | -2106253225 |
| 21 | 2364924062 |
| 22 | 67114942438 |
| 23 | -621638176430 |
| 24 | 1926931098484 |
| 25 | 14768396756732 |
| 26 | -236623058229675 |
| 27 | 1371752460097440 |
| 28 | 1098671590491324 |