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 | 4 |
| 2 | -6 |
| 3 | 24 |
| 4 | -66 |
| 5 | 208 |
| 6 | -676 |
| 7 | 2344 |
| 8 | -8226 |
| 9 | 29144 |
| 10 | -104760 |
| 11 | 381304 |
| 12 | -1398476 |
| 13 | 5162224 |
| 14 | -19172796 |
| 15 | 71582944 |
| 16 | -268439586 |
| 17 | 1010580544 |
| 18 | -3817734596 |
| 19 | 14467258264 |
| 20 | -54975633768 |
| 21 | 209430787824 |
| 22 | -799644629556 |
| 23 | 3059510616424 |
| 24 | -11728124734476 |
| 25 | 45035996273872 |
| 26 | -173215367702376 |
| 27 | 667199944815064 |