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 | 0 |
| 1 | -1 |
| 2 | 15 |
| 3 | -610 |
| 4 | 27951 |
| 5 | -1308385 |
| 6 | 61433856 |
| 7 | -2885861665 |
| 8 | 135572548335 |
| 9 | -6369013518946 |
| 10 | 299207991620175 |
| 11 | -14056406104466881 |
| 12 | 660351875572408320 |
| 13 | -31022481722865482305 |
| 14 | 1457396288941918481871 |
| 15 | -68466603097469928960610 |