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 | 2 |
| 2 | 40 |
| 3 | 8616 |
| 4 | 15639936 |
| 5 | 242230440480 |
| 6 | 32098460087825856 |
| 7 | 36433115190009846104160 |