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 | 0 |
| 2 | 0 |
| 3 | -6 |
| 4 | 12 |
| 5 | -270 |
| 6 | 1500 |
| 7 | -43806 |
| 8 | 302652 |
| 9 | -12857550 |
| 10 | 132059100 |
| 11 | -5733723006 |
| 12 | 89592628092 |
| 13 | -3922345875630 |
| 14 | 79865827177500 |
| 15 | -3844579915776606 |
| 16 | 95745315867430332 |
| 17 | -4957995149918778510 |
| 18 | 151156611852387524700 |
| 19 | -8193660691162420044606 |
| 20 | 298062602379028314213372 |