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 | 1 |
| 2 | -4 |
| 3 | 19 |
| 4 | -73 |
| 5 | 262 |
| 6 | -931 |
| 7 | 3319 |
| 8 | -11884 |
| 9 | 42679 |
| 10 | -153505 |
| 11 | 552430 |
| 12 | -1988311 |
| 13 | 7156123 |
| 14 | -25754188 |
| 15 | 92683315 |
| 16 | -333539317 |
| 17 | 1200299014 |
| 18 | -4319477491 |
| 19 | 15544370887 |
| 20 | -55939087228 |
| 21 | 201306503071 |
| 22 | -724436520553 |
| 23 | 2607011250526 |
| 24 | -9381785144287 |