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 | 36 |
| 3 | 312 |
| 4 | 3440 |
| 5 | 40956 |
| 6 | 518160 |
| 7 | 6806320 |
| 8 | 92021528 |
| 9 | 1271748364 |
| 10 | 17886165344 |
| 11 | 255159368504 |
| 12 | 3683262020928 |
| 13 | 53700117957756 |
| 14 | 789606760314200 |
| 15 | 11696040806690484 |
| 16 | 174362944317804916 |
| 17 | 2614112736300210308 |
| 18 | 39388817610142696848 |
| 19 | 596167096482669128248 |
| 20 | 9059675614901834999980 |
| 21 | 138177866602598729509112 |