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 | 1 |
| 2 | 7 |
| 3 | 56 |
| 4 | 476 |
| 5 | 4312 |
| 6 | 41468 |
| 7 | 422128 |
| 8 | 4536140 |
| 9 | 51328018 |
| 10 | 610168496 |
| 11 | 7604171722 |
| 12 | 99154078394 |
| 13 | 1350325442746 |
| 14 | 19173655721912 |
| 15 | 283420080801700 |
| 16 | 4354942891383206 |
| 17 | 69465537443190352 |
| 18 | 1148784383085885884 |
| 19 | 19673049517219904032 |
| 20 | 348483690687062619926 |