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 | 1 |
| 2 | -2 |
| 3 | 15 |
| 4 | -52 |
| 5 | 205 |
| 6 | -806 |
| 7 | 3291 |
| 8 | -13160 |
| 9 | 52393 |
| 10 | -209498 |
| 11 | 839079 |
| 12 | -3356300 |
| 13 | 13420917 |
| 14 | -53683854 |
| 15 | 214751875 |
| 16 | -859006400 |
| 17 | 3435960897 |
| 18 | -13743843762 |
| 19 | 54975632975 |
| 20 | -219902535924 |
| 21 | 879609095965 |
| 22 | -3518436366566 |
| 23 | 14073749677851 |
| 24 | -56294998711576 |
| 25 | 225179977999337 |
| 26 | -900719912066074 |