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 | 2 |
| 2 | 18 |
| 3 | 180 |
| 4 | 1734 |
| 5 | 18300 |
| 6 | 270420 |
| 7 | 5151720 |
| 8 | 96203910 |
| 9 | 1565102844 |
| 10 | 22108977596 |
| 11 | 287976684088 |
| 12 | 3835267955036 |
| 13 | 55283720348664 |
| 14 | 804522994149032 |
| 15 | 10849701753955856 |
| 16 | 150403977728200774 |
| 17 | 3086256025416536700 |
| 18 | 91156710989444409004 |
| 19 | 2687925748932854737432 |