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 | 3 |
| 4 | 7 |
| 5 | 23 |
| 6 | 108 |
| 7 | 604 |
| 8 | 3980 |
| 9 | 30186 |
| 10 | 258969 |
| 11 | 2479441 |
| 12 | 26207604 |
| 13 | 303119227 |
| 14 | 3807956707 |
| 15 | 51633582121 |
| 16 | 751604592219 |
| 17 | 11690365070546 |
| 18 | 193492748067369 |
| 19 | 3395655743755865 |
| 20 | 62980031819261211 |
| 21 | 1230967683216803500 |