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 | 0 |
| 2 | -1 |
| 3 | -6 |
| 4 | -27 |
| 5 | -100 |
| 6 | -237 |
| 7 | 742 |
| 8 | 18025 |
| 9 | 194904 |
| 10 | 1689671 |
| 11 | 12483570 |
| 12 | 72272013 |
| 13 | 155614004 |
| 14 | -4305757029 |
| 15 | -101460169442 |
| 16 | -1561477983407 |
| 17 | -20064006763728 |
| 18 | -223375429298929 |
| 19 | -2048612121431958 |
| 20 | -11401251676320843 |
| 21 | 95849085744834380 |