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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 1 |
| 6 | 30 |
| 7 | 1 |
| 8 | 720 |
| 9 | 720 |
| 10 | 40440 |
| 11 | 1 |
| 12 | 3991680 |
| 13 | 1 |
| 14 | 479006640 |
| 15 | 482630400 |
| 16 | 87178291200 |
| 17 | 1 |
| 18 | 22230464256000 |
| 19 | 1 |
| 20 | 6403681380096000 |
| 21 | 6402460884019200 |
| 22 | 2432902008216556800 |
| 23 | 1 |
| 24 | 1175091669949317120000 |
| 25 | 2432902008176640000 |
| 26 | 620448401733245666380800 |
| 27 | 620448401733239439360000 |