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 | 3 |
| 3 | -18 |
| 4 | 189 |
| 5 | -2430 |
| 6 | 34020 |
| 7 | -486972 |
| 8 | 6786261 |
| 9 | -86946372 |
| 10 | 919825956 |
| 11 | -5269375296 |
| 12 | -80180038944 |
| 13 | 3575424508272 |
| 14 | -77211406919844 |
| 15 | 1164244485947400 |
| 16 | -12342809241883386 |
| 17 | 102419678663170128 |
| 18 | -2040575112980362980 |