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 | 12 |
| 2 | 240 |
| 3 | 1344 |
| 4 | 3840 |
| 5 | 33792 |
| 6 | 5591040 |
| 7 | 49152 |
| 8 | 16711680 |
| 9 | 104595456 |
| 10 | 173015040 |
| 11 | 289406976 |
| 12 | 22900899840 |
| 13 | 201326592 |
| 14 | 116769423360 |
| 15 | 7689065201664 |
| 16 | 1095216660480 |
| 17 | 51539607552 |
| 18 | 65942866278481920 |
| 19 | 824633720832 |
| 20 | 7438196161904640 |
| 21 | 3971435999526912 |