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 | -7 |
| 3 | 57 |
| 4 | -455 |
| 5 | 3641 |
| 6 | -29127 |
| 7 | 233017 |
| 8 | -1864135 |
| 9 | 14913081 |
| 10 | -119304647 |
| 11 | 954437177 |
| 12 | -7635497415 |
| 13 | 61083979321 |
| 14 | -488671834567 |
| 15 | 3909374676537 |
| 16 | -31274997412295 |
| 17 | 250199979298361 |
| 18 | -2001599834386887 |
| 19 | 16012798675095097 |