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 | 1 |
| 2 | -6 |
| 3 | 36 |
| 4 | -251 |
| 5 | 1961 |
| 6 | -16477 |
| 7 | 145307 |
| 8 | -1326227 |
| 9 | 12420057 |
| 10 | -118666032 |
| 11 | 1152120806 |
| 12 | -11333969511 |
| 13 | 112728949041 |
| 14 | -1131701419316 |
| 15 | 11452480598696 |
| 16 | -116702578057106 |
| 17 | 1196469605151736 |
| 18 | -12332629378843566 |
| 19 | 127727907921601146 |
| 20 | -1328542834131885506 |