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 | 5 |
| 2 | 18 |
| 3 | 1 |
| 4 | 1440 |
| 5 | 1 |
| 6 | 75600 |
| 7 | 1 |
| 8 | 3628800 |
| 9 | 1 |
| 10 | 167650560 |
| 11 | 1 |
| 12 | 5230697472000 |
| 13 | 1 |
| 14 | 336259123200 |
| 15 | 1 |
| 16 | 53353114214400000 |
| 17 | 1 |
| 18 | 28100018194440192000 |
| 19 | 1 |
| 20 | 4817145976189747200000 |
| 21 | 1 |
| 22 | 91657150256046735360000 |
| 23 | 1 |
| 24 | 11856768957122205686169600000 |
| 25 | 1 |
| 26 | 1396008903899788738560000000 |
| 27 | 1 |