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 | 4 |
| 2 | 152 |
| 3 | 49920 |
| 4 | 191701440 |
| 5 | 9659304851456 |
| 6 | 6631121047328399360 |
| 7 | 63121566305846614746333184 |
| 8 | 8450364710466604643357631528951808 |
| 9 | 16116664948206611884835318695391740990586880 |