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 | 9 |
| 3 | 90 |
| 4 | 945 |
| 5 | 10440 |
| 6 | 121065 |
| 7 | 1470855 |
| 8 | 18688680 |
| 9 | 247924425 |
| 10 | 3428559573 |
| 11 | 49353455856 |
| 12 | 738477897552 |
| 13 | 11471175099726 |
| 14 | 184755890053173 |
| 15 | 3081830366508444 |
| 16 | 53182355345412138 |
| 17 | 948482464405185843 |
| 18 | 17465164002387664056 |
| 19 | 331740754587283644945 |
| 20 | 6494261833979742949884 |