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) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 45 |
| 6 | 465 |
| 7 | 5775 |
| 8 | 88515 |
| 9 | 1588545 |
| 10 | 32852925 |
| 11 | 768242475 |
| 12 | 20053670175 |
| 13 | 577971719325 |
| 14 | 18230691904425 |
| 15 | 624676513836375 |
| 16 | 23106221910646875 |
| 17 | 917643290676737625 |
| 18 | 38944796393877499125 |
| 19 | 1759004961887566267875 |