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 | -3 |
| 2 | 1 |
| 3 | 9 |
| 4 | -31 |
| 5 | 57 |
| 6 | -47 |
| 7 | -87 |
| 8 | 449 |
| 9 | -999 |
| 10 | 1201 |
| 11 | 393 |
| 12 | -5983 |
| 13 | 16377 |
| 14 | -25199 |
| 15 | 10089 |
| 16 | 70529 |
| 17 | -251943 |
| 18 | 473713 |
| 19 | -413367 |
| 20 | -654751 |
| 21 | 3617721 |
| 22 | -8234159 |
| 23 | 10231593 |
| 24 | 2241857 |
| 25 | -47651943 |
| 26 | 133988401 |
| 27 | -211357431 |
| 28 | 98118689 |