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 | 15 |
| 2 | 109 |
| 3 | 42953 |
| 4 | 2960403451017 |
| 5 | 1380531364206778111844580887042461529 |