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) |
|---|---|
| 1 | 1 |
| 2 | -13 |
| 3 | 36 |
| 4 | -258 |
| 5 | 5622 |
| 6 | -31716 |
| 7 | -83460 |
| 8 | 1766388 |
| 9 | -2952900 |
| 10 | 59171652 |
| 11 | -2614259136 |
| 12 | 25907667528 |
| 13 | -87008484996 |
| 14 | 410147565360 |
| 15 | -10353918172170 |
| 16 | 73320103253412 |
| 17 | 409638469731702 |
| 18 | -7210516315882284 |
| 19 | 18236866211886120 |
| 20 | -161388385633551558 |
| 21 | 6594430509454957926 |