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 | -64 |
| 2 | 1952 |
| 3 | -37632 |
| 4 | 512400 |
| 5 | -5207936 |
| 6 | 40618368 |
| 7 | -244952576 |
| 8 | 1124362248 |
| 9 | -3684692800 |
| 10 | 6607738816 |
| 11 | 8603838208 |
| 12 | -109557823168 |
| 13 | 389162471040 |
| 14 | -599467398400 |
| 15 | -815811136000 |
| 16 | 6834665221028 |
| 17 | -15689583552384 |
| 18 | 5284986829472 |
| 19 | 66706108652800 |
| 20 | -183175485196256 |
| 21 | 124242038746624 |