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 | -13 |
| 2 | 71 |
| 3 | -143 |
| 4 | 2653 |
| 5 | 715 |
| 6 | 51791 |
| 7 | -127127 |
| 8 | -2336027 |
| 9 | 18133687 |
| 10 | 1003761955 |
| 11 | -4095513851 |
| 12 | -11278364798537 |
| 13 | 1310672279059 |
| 14 | 9265565367737 |
| 15 | -564709715670815 |
| 16 | -387913689686252779 |
| 17 | 315149059876453231 |
| 18 | 381102197981560974797 |
| 19 | -221139612243122878019 |