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 | 0 |
| 2 | -17 |
| 3 | 399 |
| 4 | 13983 |
| 5 | 4179663 |
| 6 | 67080303 |
| 7 | 17179785663 |
| 8 | 274877776623 |
| 9 | 70368743897823 |
| 10 | 288230376151004463 |
| 11 | 4611686018426464383 |
| 12 | 18889465931478578980623 |
| 13 | 4835703278458516695998943 |