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 | -7 |
| 2 | -63 |
| 3 | -455 |
| 4 | -3199 |
| 5 | -22407 |
| 6 | -156863 |
| 7 | -1098055 |
| 8 | -7686399 |
| 9 | -53804807 |
| 10 | -376633663 |
| 11 | -2636435655 |
| 12 | -18455049599 |
| 13 | -129185347207 |
| 14 | -904297430463 |
| 15 | -6330082013255 |
| 16 | -44310574092799 |
| 17 | -310174018649607 |
| 18 | -2171218130547263 |
| 19 | -15198526913830855 |
| 20 | -106389688396815999 |