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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 15 |
| 7 | 175 |
| 8 | 1960 |
| 9 | 22449 |
| 10 | 269199 |
| 11 | 3410000 |
| 12 | 45753180 |
| 13 | 650179816 |
| 14 | 9771920158 |
| 15 | 155020511282 |
| 16 | 2589903552600 |
| 17 | 45462951235584 |
| 18 | 836599468436514 |
| 19 | 16102788580144350 |
| 20 | 323508284210923974 |
| 21 | 6770014833358706076 |
| 22 | 147290030512050486060 |
| 23 | 3325319844639779998836 |