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 | 4 |
| 2 | 26 |
| 3 | 144 |
| 4 | 736 |
| 5 | 3584 |
| 6 | 16896 |
| 7 | 77824 |
| 8 | 352256 |
| 9 | 1572864 |
| 10 | 6946816 |
| 11 | 30408704 |
| 12 | 132120576 |
| 13 | 570425344 |
| 14 | 2449473536 |
| 15 | 10468982784 |
| 16 | 44560285696 |
| 17 | 188978561024 |
| 18 | 798863917056 |
| 19 | 3367254360064 |
| 20 | 14156212207616 |
| 21 | 59373627899904 |
| 22 | 248489627877376 |
| 23 | 1037938976620544 |