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) |
|---|---|
| 0 | 1 |
| 1 | 19 |
| 2 | 121 |
| 3 | 619 |
| 4 | 3697 |
| 5 | 22389 |
| 6 | 138973 |
| 7 | 874277 |
| 8 | 5559985 |
| 9 | 35648953 |
| 10 | 230069191 |
| 11 | 1492690207 |
| 12 | 9727027549 |
| 13 | 63617931357 |
| 14 | 417371683689 |
| 15 | 2745447557409 |
| 16 | 18100412004049 |
| 17 | 119567904627743 |
| 18 | 791186114040565 |
| 19 | 5243056748156375 |