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) |
|---|---|
| 1 | 1 |
| 2 | -3 |
| 3 | 23 |
| 4 | -232 |
| 5 | 2671 |
| 6 | -33247 |
| 7 | 435732 |
| 8 | -5923596 |
| 9 | 82761455 |
| 10 | -1181085841 |
| 11 | 17143012047 |
| 12 | -252288796800 |
| 13 | 3755832135428 |
| 14 | -56459641712052 |
| 15 | 855828940166728 |
| 16 | -13066760979482436 |
| 17 | 200764834403473647 |
| 18 | -3101861571115286485 |
| 19 | 48161808069368073765 |
| 20 | -751107354803633628504 |
| 21 | 11760546724914570170423 |
| 22 | -184805245095048170080367 |
| 23 | 2913533082844307942651984 |
| 24 | -46070266558711138024672784 |
| 25 | 730480047034266200626268676 |