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 | -7 |
| 2 | 7 |
| 3 | 1993 |
| 4 | 130987 |
| 5 | 536870767 |
| 6 | 9007199254740727 |