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 | 1 |
| 3 | 45 |
| 4 | 15913 |
| 5 | 1073579193 |
| 6 | 4611686005542975085 |
| 7 | 85070591730234615801280047645054636261 |
| 8 | 28948022309329048855892746252171976961956366698726387156269151989162886489297 |