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 | -2 |
| 2 | -6 |
| 3 | -28 |
| 4 | -154 |
| 5 | -924 |
| 6 | -5852 |
| 7 | -38456 |
| 8 | -259578 |
| 9 | -1788204 |
| 10 | -12517428 |
| 11 | -88759944 |
| 12 | -636112932 |
| 13 | -4599585816 |
| 14 | -33511268088 |
| 15 | -245749299312 |
| 16 | -1812401082426 |
| 17 | -13433090375628 |
| 18 | -100001895018564 |
| 19 | -747382583822952 |
| 20 | -5605369378672140 |
| 21 | -42173731515723720 |