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 | -3 |
| 3 | 25 |
| 4 | -335 |
| 5 | 6177 |
| 6 | -144947 |
| 7 | 4128937 |
| 8 | -138327615 |
| 9 | 5327738497 |
| 10 | -231899041475 |
| 11 | 11255588133945 |
| 12 | -602683483719503 |
| 13 | 35288931375293857 |
| 14 | -2242963870471014963 |
| 15 | 153791777744471484745 |
| 16 | -11314787069889491407103 |
| 17 | 889087243145447511507969 |
| 18 | -74312052321224600661026051 |