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 | 7 |
| 4 | 31 |
| 5 | 211 |
| 6 | 1411 |
| 7 | 12601 |
| 8 | 137047 |
| 9 | 1516831 |
| 10 | 18111751 |
| 11 | 223179001 |
| 12 | 2973194071 |
| 13 | 46287964867 |
| 14 | 835826439631 |
| 15 | 15722804528341 |
| 16 | 292673102609791 |
| 17 | 5177400032329231 |
| 18 | 102538737981192607 |
| 19 | 2284570602107946601 |