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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 18 |
| 4 | 1606 |
| 5 | 565080 |
| 6 | 734774776 |
| 7 | 3523091615568 |
| 8 | 63519209389664176 |
| 9 | 4400410978376102609280 |
| 10 | 1190433705317814685295399296 |
| 11 | 1270463864957828799318424676767488 |
| 12 | 5381067966826255132459611681511359329536 |
| 13 | 90765788839403090457244128951307413371883494400 |