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 | -5 |
| 4 | -1 |
| 5 | -119 |
| 6 | 713 |
| 7 | -5039 |
| 8 | -1 |
| 9 | -5 |
| 10 | 3628679 |
| 11 | -39916799 |
| 12 | 713 |
| 13 | -6227020799 |
| 14 | 87178286159 |
| 15 | 1307674367875 |
| 16 | -1 |
| 17 | -355687428095999 |
| 18 | 713 |
| 19 | -121645100408831999 |
| 20 | 3628679 |
| 21 | 51090942171709434955 |
| 22 | 1124000727777567763199 |
| 23 | -25852016738884976639999 |
| 24 | 713 |
| 25 | -119 |
| 26 | 403291461126605629356979199 |