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 | -1 |
| 3 | -3 |
| 4 | -7 |
| 5 | -14 |
| 6 | -23 |
| 7 | -24 |
| 8 | 21 |
| 9 | 220 |
| 10 | 821 |
| 11 | 2261 |
| 12 | 4935 |
| 13 | 7814 |
| 14 | 3615 |
| 15 | -34251 |
| 16 | -179511 |
| 17 | -593420 |
| 18 | -1521779 |
| 19 | -3001089 |
| 20 | -3500101 |
| 21 | 4410846 |
| 22 | 44902907 |
| 23 | 179440150 |
| 24 | 526896835 |
| 25 | 1212055740 |
| 26 | 1976482795 |
| 27 | 697522595 |
| 28 | -10858119895 |
| 29 | -56563343774 |