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 | 0 |
| 2 | 5 |
| 3 | 0 |
| 4 | 1992 |
| 5 | 0 |
| 6 | 6167551 |
| 7 | 0 |
| 8 | 73432708224 |
| 9 | 0 |
| 10 | 2389444075877425 |
| 11 | 0 |
| 12 | 173496878823412858880 |
| 13 | 0 |
| 14 | 24573448663070711791073155 |
| 15 | 0 |
| 16 | 6168942712247503719875933929472 |
| 17 | 0 |
| 18 | 2554865971518520622455831203134760669 |
| 19 | 0 |
| 20 | 1650933998542152349112398040415912949710848 |
| 21 | 0 |