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 | 2 |
| 1 | 6 |
| 2 | 28 |
| 3 | 144 |
| 4 | 752 |
| 5 | 3936 |
| 6 | 20608 |
| 7 | 107904 |
| 8 | 564992 |
| 9 | 2958336 |
| 10 | 15490048 |
| 11 | 81106944 |
| 12 | 424681472 |
| 13 | 2223661056 |
| 14 | 11643240448 |
| 15 | 60964798464 |
| 16 | 319215828992 |
| 17 | 1671435780096 |
| 18 | 8751751364608 |
| 19 | 45824765067264 |
| 20 | 239941584945152 |
| 21 | 1256350449401856 |
| 22 | 6578336356630528 |
| 23 | 34444616342175744 |