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 | 3 |
| 4 | 15 |
| 5 | 219 |
| 6 | 7839 |
| 7 | 777069 |
| 8 | 208836207 |
| 9 | 156458382975 |
| 10 | 328208016021561 |
| 11 | 1946879656265710431 |
| 12 | 32834193098697741359313 |
| 13 | 1582809785794578499063205301 |
| 14 | 218989607557709869788340418432175 |
| 15 | 87269441106898007902526099850864517077 |