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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 696 |
| 7 | 4572 |
| 8 | 34260 |
| 9 | 290328 |
| 10 | 2751480 |
| 11 | 28426056 |
| 12 | 318900264 |
| 13 | 3874868280 |
| 14 | 50813711808 |
| 15 | 716309557440 |
| 16 | 10721493269568 |