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 | 5 |
| 2 | 7 |
| 3 | -145 |
| 4 | -1103 |
| 5 | 4925 |
| 6 | 123895 |
| 7 | 87575 |
| 8 | -15172895 |
| 9 | -88475275 |
| 10 | 2015632615 |
| 11 | 26003712575 |
| 12 | -269076694895 |
| 13 | -6962185390675 |
| 14 | 28153019652055 |
| 15 | 1895235816710375 |
| 16 | 1874863777497025 |
| 17 | -536453596325102875 |
| 18 | -3255976297539604025 |
| 19 | 157531083721635311375 |
| 20 | 1901199312366721133425 |