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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 4 |
| 6 | 144 |
| 7 | 144 |
| 8 | 576 |
| 9 | 5184 |
| 10 | 518400 |
| 11 | 518400 |
| 12 | 2073600 |
| 13 | 2073600 |
| 14 | 101606400 |
| 15 | 914457600 |
| 16 | 14631321600 |
| 17 | 14631321600 |
| 18 | 526727577600 |
| 19 | 526727577600 |
| 20 | 52672757760000 |
| 21 | 52672757760000 |
| 22 | 6373403688960000 |
| 23 | 6373403688960000 |
| 24 | 917770131210240000 |
| 25 | 22944253280256000000 |