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 | -1 |
| 3 | 12 |
| 4 | -104 |
| 5 | 1289 |
| 6 | -19605 |
| 7 | 356488 |
| 8 | -7541464 |
| 9 | 182009385 |
| 10 | -4935863537 |
| 11 | 148600324124 |
| 12 | -4918093868688 |
| 13 | 177482897072545 |
| 14 | -6936155749635541 |
| 15 | 291836667412104072 |
| 16 | -13152940374866178512 |
| 17 | 632196357654491385521 |
| 18 | -32280617841842744380161 |