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 | 25 |
| 4 | 160 |
| 5 | 1075 |
| 6 | 7671 |
| 7 | 56760 |
| 8 | 431865 |
| 9 | 3357790 |
| 10 | 26558520 |
| 11 | 213032988 |
| 12 | 1728808700 |
| 13 | 14168337265 |
| 14 | 117096909495 |
| 15 | 974842628790 |
| 16 | 8167462511193 |
| 17 | 68813778610350 |
| 18 | 582675107162175 |
| 19 | 4955767502292960 |
| 20 | 42318868510894860 |