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 | 15 |
| 3 | 15 |
| 4 | 105 |
| 5 | 1845 |
| 6 | 5175 |
| 7 | -11025 |
| 8 | 363825 |
| 9 | 4011525 |
| 10 | 46734975 |
| 11 | 367203375 |
| 12 | -909822375 |
| 13 | 105415435125 |
| 14 | 1137191430375 |
| 15 | -7081746296625 |
| 16 | 202916199110625 |
| 17 | 6031044627733125 |
| 18 | 96887972385579375 |
| 19 | 589023558627879375 |