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) |
|---|---|
| 2 | 6 |
| 3 | 15 |
| 4 | 78 |
| 5 | 990 |
| 6 | 8385 |
| 7 | 128271 |
| 8 | 2293011 |
| 9 | 46923828 |
| 10 | 1062489753 |
| 11 | 27403863105 |
| 12 | 757016521030 |
| 13 | 24028339652778 |
| 14 | 807863408487460 |
| 15 | 29499468896141965 |
| 16 | 1162871296355724735 |
| 17 | 49093065731151773880 |
| 18 | 2200689210818047715703 |
| 19 | 104755000778178115071015 |
| 20 | 5271254575974180914006953 |