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 | 4 |
| 2 | 28 |
| 3 | 232 |
| 4 | 2092 |
| 5 | 19864 |
| 6 | 195352 |
| 7 | 1970924 |
| 8 | 20277036 |
| 9 | 211864264 |
| 10 | 2241723728 |
| 11 | 23969620844 |
| 12 | 258583473640 |
| 13 | 2811005437348 |
| 14 | 30762114003572 |
| 15 | 338624821158892 |
| 16 | 3747021722921964 |
| 17 | 41656518905688504 |
| 18 | 465062224305678280 |
| 19 | 5211973807553021868 |