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 | 336 |
| 7 | 1474 |
| 8 | 8340 |
| 9 | 57756 |
| 10 | 475658 |
| 11 | 2812910 |
| 12 | 20852460 |
| 13 | 181255892 |
| 14 | 1817101242 |
| 15 | 20435345782 |
| 16 | 197871434994 |