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 | 1 |
| 2 | 5 |
| 3 | 50 |
| 4 | 850 |
| 5 | 22100 |
| 6 | 806806 |
| 7 | 40340300 |
| 8 | 2584263500 |
| 9 | 209609328500 |
| 10 | 20993420690550 |
| 11 | 2561197324247100 |
| 12 | 368819285671473000 |
| 13 | 62699278564150410000 |
| 14 | 12294076739210974071000 |
| 15 | 2766341857504878226501200 |