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 | -26 |
| 4 | -208 |
| 5 | -2570 |
| 6 | -42332 |
| 7 | -865718 |
| 8 | -21110224 |
| 9 | -597416786 |
| 10 | -19239912340 |
| 11 | -694646155742 |
| 12 | -27785653906232 |
| 13 | -1219574936748506 |
| 14 | -58274685177526300 |
| 15 | -3011159013528002150 |
| 16 | -167299112903683007392 |
| 17 | -9945379044947061586850 |
| 18 | -629870278061691615041828 |