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 | -16 |
| 2 | 144 |
| 3 | -960 |
| 4 | 5264 |
| 5 | -25056 |
| 6 | 106944 |
| 7 | -418176 |
| 8 | 1520784 |
| 9 | -5201232 |
| 10 | 16871648 |
| 11 | -52252992 |
| 12 | 155341248 |
| 13 | -445226848 |
| 14 | 1234726272 |
| 15 | -3323392128 |
| 16 | 8704504976 |
| 17 | -22234655520 |
| 18 | 55498917840 |
| 19 | -135595345600 |
| 20 | 324759439584 |