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 | -2 |
| 3 | -2 |
| 4 | 15 |
| 5 | -4 |
| 6 | -122 |
| 7 | 204 |
| 8 | 903 |
| 9 | -3374 |
| 10 | -4635 |
| 11 | 43539 |
| 12 | -13233 |
| 13 | -475123 |
| 14 | 873392 |
| 15 | 4244591 |
| 16 | -16906773 |
| 17 | -24952174 |
| 18 | 244162840 |
| 19 | -74520792 |
| 20 | -2901715074 |
| 21 | 5483226036 |
| 22 | 27740164293 |
| 23 | -112969486284 |
| 24 | -172903931727 |
| 25 | 1714556657881 |
| 26 | -513739179725 |
| 27 | -21235809823325 |