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 | -8 |
| 4 | 8 |
| 5 | -32 |
| 6 | 6112 |
| 7 | -3712 |
| 8 | 362624 |
| 9 | -71706112 |
| 10 | 3341113856 |
| 11 | -79665268736 |
| 12 | 1090547664896 |
| 13 | -38770843648 |
| 14 | 106053090598912 |
| 15 | -5507347586961932288 |
| 16 | 136847762542978039808 |
| 17 | -45309996254420664320 |
| 18 | 3447910579774800362340352 |
| 19 | -916174777198089643491328 |