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 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 40 |
| 5 | 128 |
| 6 | 408 |
| 7 | 1328 |
| 8 | 4384 |
| 9 | 14560 |
| 10 | 48576 |
| 11 | 162816 |
| 12 | 547936 |
| 13 | 1850048 |
| 14 | 6263680 |
| 15 | 21257856 |
| 16 | 72298240 |
| 17 | 246345728 |
| 18 | 840775424 |
| 19 | 2873802240 |
| 20 | 9835840512 |
| 21 | 33704557568 |
| 22 | 115622041600 |
| 23 | 397032488960 |
| 24 | 1364610270720 |
| 25 | 4694145256448 |