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 | 9 |
| 3 | 48 |
| 4 | 256 |
| 5 | 1360 |
| 6 | 7056 |
| 7 | 36000 |
| 8 | 179776 |
| 9 | 884256 |
| 10 | 4276624 |
| 11 | 20432608 |
| 12 | 96353856 |
| 13 | 449990080 |
| 14 | 2080089664 |
| 15 | 9540782208 |
| 16 | 43403888896 |
| 17 | 196212020800 |
| 18 | 881112632976 |
| 19 | 3936117388896 |
| 20 | 17487049789504 |
| 21 | 77350773736512 |
| 22 | 340574032803904 |
| 23 | 1493986588951168 |
| 24 | 6528047911024896 |