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) |
|---|---|
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 104 |
| 6 | 344 |
| 7 | 4096 |
| 8 | 14572 |
| 9 | 190652 |
| 10 | 9586984 |
| 11 | 35791472 |
| 12 | 1908874584 |
| 13 | 27487790720 |
| 14 | 104715393912 |
| 15 | 1529755308212 |
| 16 | 86607685141744 |
| 17 | 4969489243995032 |
| 18 | 19215358410149344 |
| 19 | 1117984489315857512 |
| 20 | 16865594581677305360 |
| 21 | 65588423373189982912 |