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 | -120 |
| 3 | 192 |
| 4 | 11232 |
| 5 | -69120 |
| 6 | -887808 |
| 7 | 11870208 |
| 8 | 34721280 |
| 9 | -1458585600 |
| 10 | 4612792320 |
| 11 | 124992552960 |
| 12 | -1294622392320 |
| 13 | -3918630223872 |
| 14 | 170411025235968 |
| 15 | -1023380614545408 |
| 16 | -11537631123996672 |
| 17 | 248923798395420672 |
| 18 | -709263007722504192 |
| 19 | -30740965743050883072 |
| 20 | 367936297318798589952 |
| 21 | 1683415347595793399808 |