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 | -1 |
| 3 | 11 |
| 4 | -66 |
| 5 | 629 |
| 6 | -7750 |
| 7 | 117655 |
| 8 | -2097676 |
| 9 | 43046889 |
| 10 | -999990036 |
| 11 | 25937424611 |
| 12 | -743008622708 |
| 13 | 23298085122493 |
| 14 | -793714765724686 |
| 15 | 29192926025492783 |
| 16 | -1152921504875290680 |
| 17 | 48661191875666868497 |
| 18 | -2185911559727680349982 |
| 19 | 104127350297911241532859 |