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 | 3 |
| 3 | 30 |
| 4 | 1050 |
| 5 | 132300 |
| 6 | 61122600 |
| 7 | 104886381600 |
| 8 | 674943865596000 |
| 9 | 16407885372638760000 |
| 10 | 1515727634953623371280000 |
| 11 | 534621388490302221024396480000 |
| 12 | 722849817707190846398223943885440000 |
| 13 | 3759035907022704558524683975387453632000000 |