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 | 0 |
| 1 | 0 |
| 2 | 4 |
| 3 | 16 |
| 4 | 76 |
| 5 | 304 |
| 6 | 1264 |
| 7 | 5056 |
| 8 | 20404 |
| 9 | 81616 |
| 10 | 327184 |
| 11 | 1308736 |
| 12 | 5237776 |
| 13 | 20951104 |
| 14 | 83815744 |
| 15 | 335262976 |
| 16 | 1341097036 |
| 17 | 5364388144 |
| 18 | 21457733104 |
| 19 | 85830932416 |
| 20 | 343324451056 |
| 21 | 1373297804224 |
| 22 | 5493194102464 |
| 23 | 21972776409856 |
| 24 | 87891117178864 |