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 | 3 |
| 2 | 15 |
| 3 | 133 |
| 4 | 2025 |
| 5 | 37851 |
| 6 | 1030367 |
| 7 | 36362925 |
| 8 | 1606008513 |
| 9 | 87656896891 |
| 10 | 5778121715415 |
| 11 | 452794797220965 |
| 12 | 41609568918940625 |