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 | -25 |
| 2 | 250 |
| 3 | -1125 |
| 4 | 625 |
| 5 | 15495 |
| 6 | -54375 |
| 7 | -20625 |
| 8 | 413325 |
| 9 | -246425 |
| 10 | -1719150 |
| 11 | -854425 |
| 12 | 11885650 |
| 13 | 13624250 |
| 14 | -73600100 |
| 15 | -65950175 |
| 16 | 191784500 |
| 17 | 512802500 |
| 18 | 23353075 |
| 19 | -2854336325 |
| 20 | -2372290275 |
| 21 | 4919896900 |
| 22 | 19737007600 |