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 | 9 |
| 2 | 69 |
| 3 | 541 |
| 4 | 4231 |
| 5 | 33101 |
| 6 | 258953 |
| 7 | 2025831 |
| 8 | 15848391 |
| 9 | 123984439 |
| 10 | 969949627 |
| 11 | 7588067405 |
| 12 | 59362636295 |
| 13 | 464403174075 |
| 14 | 3633098554089 |
| 15 | 28422297349753 |
| 16 | 222352070721709 |
| 17 | 1739494972761653 |
| 18 | 13608340819322255 |
| 19 | 106460175369651261 |