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 | 3 |
| 2 | 1 |
| 3 | -45 |
| 4 | -255 |
| 5 | -477 |
| 6 | 2689 |
| 7 | 25203 |
| 8 | 82945 |
| 9 | -90045 |
| 10 | -2379519 |
| 11 | -11581677 |
| 12 | -12063999 |
| 13 | 197669475 |
| 14 | 1423716225 |
| 15 | 3645266355 |
| 16 | -12180238335 |
| 17 | -156702949245 |
| 18 | -626511576575 |
| 19 | 51239061075 |
| 20 | 15179398450945 |
| 21 | 87687927568035 |
| 22 | 151934475887745 |