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) |
|---|---|
| 4 | 1 |
| 5 | 20 |
| 6 | 276 |
| 7 | 3276 |
| 8 | 35960 |
| 9 | 376992 |
| 10 | 3838380 |
| 11 | 38320568 |
| 12 | 377348994 |
| 13 | 3679075400 |
| 14 | 35607051480 |
| 15 | 342700125300 |
| 16 | 3284214703056 |
| 17 | 31368725759168 |
| 18 | 298824321028320 |
| 19 | 2840671544105280 |
| 20 | 26958221130508525 |
| 21 | 255485622301674660 |