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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 30960 |
| 9 | 172200 |
| 10 | 899064 |
| 11 | 4553166 |
| 12 | 22934774 |
| 13 | 116914351 |
| 14 | 610093513 |
| 15 | 3222826972 |
| 16 | 17101449940 |
| 17 | 90706002192 |
| 18 | 479654768640 |
| 19 | 2527274267136 |
| 20 | 13280313508416 |
| 21 | 69734129749632 |
| 22 | 366283822765632 |
| 23 | 1925290900630896 |
| 24 | 10126754515065868 |