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 | -6 |
| 2 | 29 |
| 3 | -138 |
| 4 | 660 |
| 5 | -3162 |
| 6 | 15151 |
| 7 | -72594 |
| 8 | 347819 |
| 9 | -1666500 |
| 10 | 7984680 |
| 11 | -38256900 |
| 12 | 183299821 |
| 13 | -878242206 |
| 14 | 4207911209 |
| 15 | -20161313838 |
| 16 | 96598657980 |
| 17 | -462831976062 |
| 18 | 2217561222331 |
| 19 | -10624974135594 |
| 20 | 50907309455639 |
| 21 | -243911573142600 |
| 22 | 1168650556257360 |
| 23 | -5599341208144200 |