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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 225 |
| 5 | 3224 |
| 6 | 29274 |
| 7 | 215900 |
| 8 | 1412275 |
| 9 | 8541876 |
| 10 | 48876212 |
| 11 | 268288008 |
| 12 | 1425694725 |
| 13 | 7381073920 |
| 14 | 37399844174 |
| 15 | 186110137668 |
| 16 | 911952794935 |
| 17 | 4409472232060 |
| 18 | 21073909951080 |
| 19 | 99688911645264 |
| 20 | 467292120940425 |