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 | 275 |
| 3 | -1750 |
| 4 | 7300 |
| 5 | -23255 |
| 6 | 73150 |
| 7 | -252625 |
| 8 | 796275 |
| 9 | -2137925 |
| 10 | 5733355 |
| 11 | -16646550 |
| 12 | 45304475 |
| 13 | -111461125 |
| 14 | 280683700 |
| 15 | -735052700 |
| 16 | 1815283450 |
| 17 | -4275549750 |
| 18 | 10301217900 |
| 19 | -24923579950 |
| 20 | 58128778485 |
| 21 | -133132664600 |