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) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 40 |
| 3 | 208 |
| 4 | 1024 |
| 5 | 4864 |
| 6 | 22528 |
| 7 | 102400 |
| 8 | 458752 |
| 9 | 2031616 |
| 10 | 8912896 |
| 11 | 38797312 |
| 12 | 167772160 |
| 13 | 721420288 |
| 14 | 3087007744 |
| 15 | 13153337344 |
| 16 | 55834574848 |
| 17 | 236223201280 |
| 18 | 996432412672 |
| 19 | 4191888080896 |
| 20 | 17592186044416 |
| 21 | 73667279060992 |