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 | 22 |
| 3 | 125 |
| 4 | 669 |
| 5 | 3410 |
| 6 | 16677 |
| 7 | 78369 |
| 8 | 359110 |
| 9 | 1612613 |
| 10 | 7133274 |
| 11 | 31185350 |
| 12 | 135062165 |
| 13 | 580556958 |
| 14 | 2480278767 |
| 15 | 10542976739 |
| 16 | 44626102826 |
| 17 | 188215850830 |
| 18 | 791374442571 |
| 19 | 3318478309647 |
| 20 | 13882441625034 |
| 21 | 57952990683107 |