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) |
|---|---|
| 3 | 1 |
| 4 | 168 |
| 5 | -12636 |
| 6 | 392832 |
| 7 | -7335174 |
| 8 | 92207808 |
| 9 | -804651624 |
| 10 | 4626614784 |
| 11 | -11834988165 |
| 12 | -73870961696 |
| 13 | 1115908456740 |
| 14 | -7498139072256 |
| 15 | 32630722986078 |
| 16 | -90379426346496 |
| 17 | 94395618447768 |
| 18 | 450271639673856 |
| 19 | -2625847472007243 |
| 20 | 6203580643521072 |
| 21 | -3151366507609936 |