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 | 0 |
| 1 | 1 |
| 2 | 2052 |
| 3 | 177156 |
| 4 | 4202512 |
| 5 | 48828150 |
| 6 | 363524112 |
| 7 | 1977326792 |
| 8 | 8606744640 |
| 9 | 31382654013 |
| 10 | 100195363800 |
| 11 | 285311670732 |
| 12 | 744500215872 |
| 13 | 1792160394206 |
| 14 | 4057474577184 |
| 15 | 8650199741400 |
| 16 | 17626613022976 |
| 17 | 34271896307922 |
| 18 | 64397206034676 |
| 19 | 116490258898580 |
| 20 | 205200886312800 |