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 | -8 |
| 2 | 32 |
| 3 | -512 |
| 4 | 4608 |
| 5 | -73728 |
| 6 | 819200 |
| 7 | -13107200 |
| 8 | 160563200 |
| 9 | -2569011200 |
| 10 | 33294385152 |
| 11 | -532710162432 |
| 12 | 7161992183808 |
| 13 | -114591874940928 |
| 14 | 1580900152246272 |
| 15 | -25294402435940352 |
| 16 | 355702534255411200 |
| 17 | -5691240548086579200 |
| 18 | 81223136710964019200 |
| 19 | -1299570187375424307200 |
| 20 | 18765793505701126995968 |