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) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 20 |
| 5 | 155 |
| 6 | 1716 |
| 7 | 24654 |
| 8 | 434155 |
| 9 | 9043990 |
| 10 | 217457456 |
| 11 | 5926620029 |
| 12 | 180538177590 |
| 13 | 6078622845750 |
| 14 | 224156328707221 |
| 15 | 8984765008810504 |
| 16 | 388939866084222200 |
| 17 | 18083736252080051435 |
| 18 | 898779656769444326136 |
| 19 | 47551736771345760732954 |