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 | -2 |
| 3 | 14 |
| 4 | -152 |
| 5 | 2264 |
| 6 | -42832 |
| 7 | 982512 |
| 8 | -26484096 |
| 9 | 820207488 |
| 10 | -28692711168 |
| 11 | 1118821622016 |
| 12 | -48112717347840 |
| 13 | 2261868010650624 |
| 14 | -115400220781209600 |
| 15 | 6350152838136428544 |
| 16 | -374874781697133871104 |
| 17 | 23632196147497381625856 |
| 18 | -1584445791263626895228928 |