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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 28 |
| 6 | 550 |
| 7 | 28456 |
| 8 | 4134861 |
| 9 | 1781622569 |
| 10 | 2407100396065 |
| 11 | 10660643722901700 |
| 12 | 159393017165624876022 |
| 13 | 8189716815725538561261887 |