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 | -7 |
| 3 | 70 |
| 4 | -798 |
| 5 | 9737 |
| 6 | -124124 |
| 7 | 1631041 |
| 8 | -21911758 |
| 9 | 299371219 |
| 10 | -4144898772 |
| 11 | 58007463920 |
| 12 | -819038646307 |
| 13 | 11650826921489 |
| 14 | -166786290656152 |
| 15 | 2400680788969898 |
| 16 | -34719393978035312 |
| 17 | 504223005531434252 |
| 18 | -7349846348644213981 |
| 19 | 107489242662154350550 |