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 | 17 |
| 3 | 77 |
| 4 | 374 |
| 5 | 1959 |
| 6 | 11085 |
| 7 | 67500 |
| 8 | 438485 |
| 9 | 3004985 |
| 10 | 21485222 |
| 11 | 158744467 |
| 12 | 1202966761 |
| 13 | 9297312916 |
| 14 | 72981656937 |
| 15 | 580105886517 |
| 16 | 4658713796790 |
| 17 | 37736326098735 |
| 18 | 307913254091925 |
| 19 | 2528335636842300 |
| 20 | 20875157745756429 |