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 | 2 |
| 2 | 1 |
| 3 | 4 |
| 4 | -13 |
| 5 | 142 |
| 6 | -1931 |
| 7 | 36296 |
| 8 | -893273 |
| 9 | 27927346 |
| 10 | -1081725559 |
| 11 | 50861556172 |
| 12 | -2854289486309 |
| 13 | 188475382997654 |
| 14 | -14467150771771043 |
| 15 | 1277417937676246672 |
| 16 | -128570745743431055281 |
| 17 | 14632875988040732946106 |
| 18 | -1869882665740777942166543 |
| 19 | 266593648798424693540514836 |