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 | 0 |
| 2 | -511 |
| 3 | -19682 |
| 4 | -262143 |
| 5 | -1953124 |
| 6 | -10077695 |
| 7 | -40353606 |
| 8 | -134217727 |
| 9 | -387420488 |
| 10 | -999999999 |
| 11 | -2357947690 |
| 12 | -5159780351 |
| 13 | -10604499372 |
| 14 | -20661046783 |
| 15 | -38443359374 |
| 16 | -68719476735 |
| 17 | -118587876496 |
| 18 | -198359290367 |