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) |
|---|---|
| 3 | 0 |
| 4 | 1 |
| 5 | 61 |
| 6 | 2836 |
| 7 | 129288 |
| 8 | 6160640 |
| 9 | 313921008 |
| 10 | 17239040000 |
| 11 | 1021644763392 |
| 12 | 65244849242112 |
| 13 | 4477975127425280 |
| 14 | 329252714454974464 |
| 15 | 25850313756000000000 |
| 16 | 2160223055912342913024 |
| 17 | 191558954408834121740288 |
| 18 | 17973564914103712921681920 |